update otr.js to 0.1.4
abstract out ensuring otr
better switching between dialogs
getting somewhere
use si-filetransfer
send chunks
blob from data
encrypt then mac
link, don't open
PNG Compression improvements
Support window.crypto.getRandomValues() in Firefox
Merge pull request #266 from arlolra/firefox

Support window.crypto.getRandomValues() in Firefox
Some cleanup, thanks to @kaosdynamics (fix #238)
Probably the last PNG Compression improvement
Merge pull request #268 from neheb/master

Probably the last PNG compression Improvement.
Push PNGs
Merge pull request #247 from arlolra/transfer

File Transfer
Major cleanup for @arlolra's file transfer commit #247
Some UI tweaks for #247
Redefine fileSize and chunkSize according to IRC conversation with @arlolra  and @koolfy