Fixed asynchronous Activity leaks in Fragments
If a Fragment has been detached its `getActivity()` method will return null, providing numerous crash possibilities within the app.
My approach to fixing this is to make Fragments use their own `runOnUiThreadUnlessDestroyed` method, which also checks if the Fragment has been detached before running the Runnable
Closes#714
See merge request !387
Let only the creator invite new members to private groups
A little bug I noticed when reviewing the implementation of the invitation protocol.
See merge request !383
Implement UX for viewing the membership of a private group
This MR is the second and last MR to address #678. The first part is in !377.
Closes#678
See merge request !364
Implement UX for leaving a group
This MR also includes the creator's part of the UX for dissolving a group since it is almost the same.
Closes#671
See merge request !367
Remove forum content type and change bodies to string
Also removes support for anonymous forum posts.
This MR depends on !360.
Closes#698, #681
See merge request !370
Refactor contact lists, their adapters and items
This was supposed to be a preparation for #678 to make the contacts lists cleaner and easier to re-use for different use-cases. Turns out #678 can't use this work, but it is probably nice to have anyway.
During this work, support for multiple identities has been removed from the various contact lists.
See merge request !363
Disable EmojiTextView software layer rendering when cache is too small
This needs to be tested if it works as intended on several devices.
See merge request !362
Limit scene transition animations to API 23 and above
to work-around [android bug #224270](https://code.google.com/p/android/issues/detail?id=224270).
This is only necessary if the transitioning view might not be available anymore when the exit transition is made.
Closes#686
See merge request !361
