Image optimization 2

I found out that AdvPNG has a nice new compression algorithm. It appears that using both PNGOUT and AdvPNG gives much better results than using either one alone.

### File size reductions
Total change -63354
<table>
<tr><th>Size change</th><th>File path</th></tr>
<tr><td>-1257</td><td>assets/img/free-100/enigmail.png</td></tr>
<tr><td>-1239</td><td>assets/img/free-100/namecoin.png</td></tr>
<tr><td>-1228</td><td>assets/img/free-100/otr.png</td></tr>
<tr><td>-1196</td><td>assets/img/free-100/webpg.png</td></tr>
<tr><td>-1193</td><td>assets/img/free-100/clawsmail.png</td></tr>
<tr><td>-1167</td><td>assets/img/free-100/startpage.png</td></tr>
<tr><td>-1163</td><td>assets/img/free-100/projectmeshnet.png</td></tr>
<tr><td>-1127</td><td>assets/img/free-100/fixtracking.png</td></tr>
<tr><td>-1091</td><td>assets/img/free-100/icedove.png</td></tr>
<tr><td>-1085</td><td>assets/img/free-100/onionbrowser.png</td></tr>
<tr><td>-1079</td><td>assets/img/free-100/icecat.png</td></tr>
<tr><td>-1056</td><td>assets/img/free-100/thunderbird.png</td></tr>
<tr><td>-1047</td><td>assets/img/free-100/bitcoin.png</td></tr>
<tr><td>-1032</td><td>assets/img/free-100/debian.png</td></tr>
<tr><td>-1029</td><td>assets/img/free-100/openstreetmap.png</td></tr>
<tr><td>-1026</td><td>assets/img/free-100/duckduckgo.png</td></tr>
<tr><td>-997</td><td>assets/img/free-100/tor.png</td></tr>
<tr><td>-989</td><td>assets/img/free-100/bsd.png</td></tr>
<tr><td>-986</td><td>assets/img/free-100/mailvelope.png</td></tr>
<tr><td>-973</td><td>assets/img/free-100/wordpress.png</td></tr>
<tr><td>-969</td><td>assets/img/free-100/yacy.png</td></tr>
<tr><td>-966</td><td>assets/img/free-100/seeks.png</td></tr>
<tr><td>-961</td><td>assets/img/free-100/firefox.png</td></tr>
<tr><td>-956</td><td>assets/img/free-100/adium.png</td></tr>
<tr><td>-920</td><td>assets/img/free-100/kmail.png</td></tr>
<tr><td>-918</td><td>assets/img/free-100/retroshare.png</td></tr>
<tr><td>-915</td><td>assets/img/free-100/trisquel.png</td></tr>
<tr><td>-907</td><td>assets/img/free-100/sparkleshare.png</td></tr>
<tr><td>-902</td><td>assets/img/free-100/linux.png</td></tr>
<tr><td>-899</td><td>assets/img/free-100/pidgin.png</td></tr>
<tr><td>-879</td><td>assets/img/prop/google-picasa.png</td></tr>
<tr><td>-864</td><td>assets/img/free-100/bitmessage.png</td></tr>
<tr><td>-845</td><td>assets/img/free-100/ubuntu.png</td></tr>
<tr><td>-758</td><td>assets/img/free-100/jitsi.png</td></tr>
<tr><td>-743</td><td>assets/img/free-100/mumble.png</td></tr>
<tr><td>-725</td><td>assets/img/free-100/chatsecure.png</td></tr>
<tr><td>-697</td><td>assets/img/free-100/linphone.png</td></tr>
<tr><td>-693</td><td>assets/img/free-100/mediagoblin.png</td></tr>
<tr><td>-685</td><td>assets/img/free-100/pumpio.png</td></tr>
<tr><td>-676</td><td>assets/img/free-100/xabber.png</td></tr>
<tr><td>-673</td><td>assets/img/free-100/evolution.png</td></tr>
<tr><td>-656</td><td>assets/img/free-100/salutatoi.png</td></tr>
<tr><td>-636</td><td>assets/img/free-100/gibberbot.png</td></tr>
<tr><td>-635</td><td>assets/img/free-100/gnupg.png</td></tr>
<tr><td>-616</td><td>assets/img/free/projectmeshnet.png</td></tr>
<tr><td>-577</td><td>assets/img/free-100/orbot.png</td></tr>
<tr><td>-562</td><td>assets/img/free-100/lorea.png</td></tr>
<tr><td>-547</td><td>assets/img/free-100/cryptocat.png</td></tr>
<tr><td>-517</td><td>assets/img/free-100/tails.png</td></tr>
<tr><td>-482</td><td>assets/img/free/onionbrowser.png</td></tr>
<tr><td>-479</td><td>assets/img/free-100/nightweb.png</td></tr>
<tr><td>-458</td><td>assets/img/free-100/textsecure.png</td></tr>
<tr><td>-441</td><td>assets/img/free/liberte.png</td></tr>
<tr><td>-407</td><td>assets/img/free/icedove.png</td></tr>
<tr><td>-397</td><td>assets/img/free-100/redphone.png</td></tr>
<tr><td>-392</td><td>assets/img/free/wordpress.png</td></tr>
<tr><td>-391</td><td>assets/img/free/noscript.png</td></tr>
<tr><td>-390</td><td>assets/img/free-100/fn.png</td></tr>
<tr><td>-384</td><td>assets/img/free-100/cyanogenmod.png</td></tr>
<tr><td>-376</td><td>assets/img/free/bitcoin.png</td></tr>
<tr><td>-375</td><td>assets/img/free-100/friendica.png</td></tr>
<tr><td>-363</td><td>assets/img/free/enigmail.png</td></tr>
<tr><td>-362</td><td>assets/img/free/webpg.png</td></tr>
<tr><td>-356</td><td>assets/img/free-100/gnusocial.png</td></tr>
<tr><td>-354</td><td>assets/img/free/retroshare.png</td></tr>
<tr><td>-342</td><td>assets/img/free/icecat.png</td></tr>
<tr><td>-335</td><td>assets/img/free/mailvelope.png</td></tr>
<tr><td>-322</td><td>assets/img/free/clawsmail.png</td></tr>
<tr><td>-305</td><td>assets/img/free/kmail.png</td></tr>
<tr><td>-301</td><td>assets/img/free-100/prohibition.png</td></tr>
<tr><td>-295</td><td>assets/img/free/thunderbird.png</td></tr>
<tr><td>-293</td><td>assets/img/free/trisquel.png</td></tr>
<tr><td>-279</td><td>assets/img/free-100/diaspora.png</td></tr>
<tr><td>-278</td><td>assets/img/free/ethercalc.png</td></tr>
<tr><td>-275</td><td>assets/img/free-100/replicant.png</td></tr>
<tr><td>-271</td><td>assets/img/free/startpage.png</td></tr>
<tr><td>-264</td><td>assets/img/free/namecoin.png</td></tr>
<tr><td>-261</td><td>assets/ico/apple-touch-icon-144-precomposed.png</td></tr>
<tr><td>-261</td><td>assets/img/free/buddycloud.png</td></tr>
<tr><td>-255</td><td>assets/img/free/openstreetmap.png</td></tr>
<tr><td>-254</td><td>assets/img/free/linux.png</td></tr>
<tr><td>-248</td><td>assets/img/free/fixtracking.png</td></tr>
<tr><td>-238</td><td>assets/img/free/duckduckgo.png</td></tr>
<tr><td>-231</td><td>assets/img/free-100/seafile.png</td></tr>
<tr><td>-229</td><td>assets/img/free/bsd.png</td></tr>
<tr><td>-218</td><td>assets/img/free-100/piwik.png</td></tr>
<tr><td>-218</td><td>assets/img/free/mumble.png</td></tr>
<tr><td>-212</td><td>assets/img/free-100/etherpad.png</td></tr>
<tr><td>-210</td><td>assets/ico/apple-touch-icon-114-precomposed.png</td></tr>
<tr><td>-205</td><td>assets/img/free/otr.png</td></tr>
<tr><td>-202</td><td>assets/img/free-100/piwigo.png</td></tr>
<tr><td>-195</td><td>assets/img/free-100/tormail.png</td></tr>
<tr><td>-195</td><td>assets/img/free/pidgin.png</td></tr>
<tr><td>-187</td><td>assets/img/free-100/opennic.png</td></tr>
<tr><td>-181</td><td>assets/img/free/yacy.png</td></tr>
<tr><td>-174</td><td>assets/img/free/sparkleshare.png</td></tr>
<tr><td>-173</td><td>assets/img/free/tails.png</td></tr>
<tr><td>-161</td><td>assets/img/free/firefox.png</td></tr>
<tr><td>-148</td><td>assets/img/free/evolution.png</td></tr>
<tr><td>-142</td><td>assets/img/free/linphone.png</td></tr>
<tr><td>-140</td><td>assets/img/free/lorea.png</td></tr>
<tr><td>-138</td><td>assets/img/free-100/zenphoto.png</td></tr>
<tr><td>-138</td><td>assets/img/free/cryptocoin.png</td></tr>
<tr><td>-135</td><td>assets/img/free/chatsecure.png</td></tr>
<tr><td>-132</td><td>assets/img/free/adium.png</td></tr>
<tr><td>-130</td><td>assets/img/free/fedora.png</td></tr>
<tr><td>-129</td><td>assets/img/free-100/movim.png</td></tr>
<tr><td>-129</td><td>assets/img/free/tor.png</td></tr>
<tr><td>-127</td><td>assets/img/free-100/linuxmint.png</td></tr>
<tr><td>-126</td><td>assets/img/free/fdroid.png</td></tr>
<tr><td>-125</td><td>assets/img/free/diaspora.png</td></tr>
<tr><td>-121</td><td>assets/img/free-100/owncloud.png</td></tr>
<tr><td>-120</td><td>assets/img/free/cryptocat.png</td></tr>
<tr><td>-115</td><td>assets/img/free-100/ethercalc.png</td></tr>
<tr><td>-114</td><td>assets/img/free/debian.png</td></tr>
<tr><td>-114</td><td>assets/img/prop/apple-icloud.png</td></tr>
<tr><td>-108</td><td>assets/img/free/gnusocial.png</td></tr>
<tr><td>-107</td><td>assets/img/free/pumpio.png</td></tr>
<tr><td>-106</td><td>assets/img/prop/instagram.png</td></tr>
<tr><td>-104</td><td>assets/ico/apple-touch-icon-72-precomposed.png</td></tr>
<tr><td>-98</td><td>assets/img/free/jitsi.png</td></tr>
<tr><td>-92</td><td>assets/img/free/owncloud.png</td></tr>
<tr><td>-90</td><td>assets/img/free/httpseverywhere.png</td></tr>
<tr><td>-89</td><td>assets/img/free/opennic.png</td></tr>
<tr><td>-87</td><td>assets/img/free/tormail.png</td></tr>
<tr><td>-85</td><td>assets/img/free/disconnect.png</td></tr>
<tr><td>-80</td><td>assets/img/free-100/tentio.png</td></tr>
<tr><td>-80</td><td>assets/img/free/mediagoblin.png</td></tr>
<tr><td>-79</td><td>assets/ico/apple-touch-icon-57-precomposed.png</td></tr>
<tr><td>-78</td><td>assets/img/free-100/syndie.png</td></tr>
<tr><td>-78</td><td>assets/img/free/etherpad.png</td></tr>
<tr><td>-73</td><td>assets/img/free/zenphoto.png</td></tr>
<tr><td>-71</td><td>assets/img/prop/ios.png</td></tr>
<tr><td>-70</td><td>assets/img/prop/apple-osx.png</td></tr>
<tr><td>-63</td><td>assets/img/free/adblockedge.png</td></tr>
<tr><td>-56</td><td>assets/img/free/movim.png</td></tr>
<tr><td>-52</td><td>assets/img/free/prohibition.png</td></tr>
<tr><td>-49</td><td>assets/img/free-100/tahoe-lafs.png</td></tr>
<tr><td>-48</td><td>assets/ico/favicon-retina.png</td></tr>
<tr><td>-48</td><td>assets/img/free/gibberbot.png</td></tr>
<tr><td>-46</td><td>assets/img/free-100/i2p.png</td></tr>
<tr><td>-44</td><td>assets/img/free/salutatoi.png</td></tr>
<tr><td>-41</td><td>assets/img/free/tentio.png</td></tr>
<tr><td>-39</td><td>assets/ico/favicon.png</td></tr>
<tr><td>-39</td><td>assets/img/free/noblogs.png</td></tr>
<tr><td>-39</td><td>assets/img/free/seeks.png</td></tr>
<tr><td>-37</td><td>assets/img/free/autistici.png</td></tr>
<tr><td>-34</td><td>assets/img/free/csipsimple.png</td></tr>
<tr><td>-32</td><td>assets/img/free-100/csipsimple.png</td></tr>
<tr><td>-22</td><td>assets/img/free/xabber.png</td></tr>
<tr><td>-11</td><td>assets/img/free/gnupg.png</td></tr>
<tr><td>-11</td><td>assets/img/prop/groupwise.png</td></tr>
<tr><td>-4</td><td>assets/img/prop/tumblr.png</td></tr>
<tr><td>-2</td><td>assets/img/free-100/riseup.png</td></tr>
<tr><td>-1</td><td>assets/img/free-100/surespot.png</td></tr>
<tr><td>-1</td><td>assets/img/free/friendica.png</td></tr>
<tr><td>-1</td><td>assets/img/free/linuxmint.png</td></tr>
<tr><td>-1</td><td>assets/img/free/orbot.png</td></tr>
<tr><td>-1</td><td>assets/img/prop/google-chrome.png</td></tr>
<tr><td>-1</td><td>assets/img/prop/linkedin.png</td></tr>
<tr><td>-1</td><td>assets/img/prop/ms-outlook.png</td></tr>
</table>