Encode transport properties more compactly in QR codes
The [original BQP spec](https://code.briarproject.org/akwizgran/briar/wikis/BQP) described a compact encoding for transport properties, with the goal of making the QR code as small as possible. At some point during the implementation, I asked @str4d to use TransportIds and TransportProperties instead, as described in the [current spec](https://code.briarproject.org/akwizgran/briar-spec/blob/master/protocols/BQP.md). That was a mistake.
Using the original format reduces the payload from 60 to 34 bytes (43% smaller) for Bluetooth only, and from 96 to 49 bytes (49% smaller) for Bluetooth and LAN. This makes it easier to scan codes from low-resolution screens using fixed-focus and/or low-resolution cameras. Using this branch I can exchange codes between the Sony Xperia Tipo (320x480 screen, fixed focus, 640x480 preview size) and the Huawei Ascend Y300 (480x800 screen, infinity focus, 1280x720 preview size).
This also removes an obstacle to implementing #558, as TransportIds are no longer included in QR codes.
Closes#346.
See merge request !394
Mark private messages read properly
Depends on !386.
This branch uses the same approach as forums to mark messages read, i.e. each message is marked read when it becomes visible, rather than marking all messages read in a batch when the activity finishes. This fixes two problems: messages not being marked read when isFinishing() is false, for example when leaving the activity via the home button, and a race condition between updating and loading the group count when leaving the activity, resulting in a stale unread message count in the contact list.
Closes#196.
See merge request !388
Return to group after not inviting new members
This MR also closes the keyboard when returning from the message fragment.
Closes#735
See merge request !389
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
