copy/save/delete is accessed via longpress for all media messages, just
like for simple text messages.
Notes
-----
We don't support saving audio attachments as it's not clear where they should go.
(I don't think users expect them to end up in their iTunes library.)
There is still no UX for "pasting" media into Signal.
Removed the now redundant (and confusing) "share" button interface.
//FREEBIE
- Using same clang format file for old and new files.
- Moving out all TextSecure code to allow other clients (OS X, iOS) to
integrate easily TextSecure functionality.
- Use TextSecure API to signup.
Implemented using corbett's suggestion in issue #525. Uses
Flipboard/FLAnimatedImage in an AttachmentAdapter. Detects gifs using
new Animated category in MIMETypeUtil.
Backwards compatible with previous versions of Signal on iOS for both
sending and receiving Gifs, though they are sent/received in older
versions as UIImage and won't animate. Gifs also animate on both ends of
conversations with TextSecure users on Android.
//FREEBIE