New images

--HG--
rename : app/images/intro_1.png => app/images/introduction_step1_hd.png
rename : app/images/intro_2.png => app/images/introduction_step2_hd.png
rename : app/images/intro_3.png => app/images/introduction_step3_hd.png
rename : app/images/background_hd.png => app/images/overhang_hd.png
rename : app/images/background_sd.jpg => app/images/overhang_sd.png
rename : app/images/select_bkgnd.png => app/images/selectbar_hd.png
Add support for passing buttons into showMessage and cleanup showPopup
Switch over to the new images in code
Misc cleanup in utils
Add cleanup and an error popup in video player
Add a popup menu in recent history
Switch to use about screen and not the help screen
Merge mfinkle's last hg changes.