Cryptocat 2.1.6

- Big fixes to file transfer! If you've been experiencing problems,
this update should help.
- File transfer now works fully in Cryptocat for Safari and Mac, as
well as Chrome and Firefox.
- Cryptocat for Mac has been rewritten from scratch.
- Cryptocat for Mac now supports creating multiple windows for multiple
conversations.
- Some internal optimizations and updates.
- Bug fixes.
- Updated Russian and Farsi translations.