and turn them into a regular string.

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

Add methods and hooks to PrivateGroupManager related to members and removal

This MR is the first of two MRs related to #678.

See merge request !377

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

Implement protocol for private group messaging

Closes #708

See merge request !360

Also removes support for anonymous forum posts.
Closes #698

Implement UX for showing and answering private group invitations

As usual, this MR contains several logically separate commits that could be split out into smaller MRs if desired. It consists of two main parts:
* Showing open invitations in the list of private groups with a snackbar
* Showing invitations and responses in the private conversation

For both parts, the existing code was refactored to allow for a smooth implementation and to leave maintainable code behind.

![device-2016-10-18-101549](/uploads/66582dbe97736fdcd2498e87e1c7dfd1/device-2016-10-18-101549.png)
![device-2016-10-18-101612](/uploads/8c25eff8171f330796a55cb27cdb2552/device-2016-10-18-101612.png)
![device-2016-10-18-101534](/uploads/ebba4c0a2c0f727dcadac8c2ec57b48f/device-2016-10-18-101534.png)

Closes #707

See merge request !357

ProtocolStateException for client protocols

Methods that implement local actions in a client protocol (for example, accepting an invitation) can throw this exception to indicate that the action wasn't taken because the action isn't applicable to the current state. This can happen if the protocol state machine is updated by an incoming message and the user takes an action before the UI has been updated.

See merge request !368

Fix proguard notes about unkept descriptor classes

Closes #688

See merge request !366

Fix crash when navigating back in contact selector

Closes #718

See merge request !365

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

Implement UX for creating a private group

This MR allows the user to create a new private group and select contacts to be invited into the group.

There are currently 6 commits starting with some small refactoring for code reuse and making more functionality available in the backend. Each commit could be split up into a dedicated MR if desired.

![create-groups](/uploads/5229f102ee2611c05d5e9d1e2aac510d/create-groups.gif)

Closes #661

See merge request !353