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
Private group invitation protocol
This branch implements the private group invitation protocol. The implementation is something of an experiment with a new way of writing client protocols.
We start with a role enum that lists the roles in the protocol, and a state enum for each role, which lists the states in the role's state machine. Then there's a session class, parameterised by the state class and therefore by the role, which represents the session information held by that role. Then there's an engine interface, parameterised by the session class and therefore by the role, which encapsulates the protocol logic for the role. Most of this stuff can be created pretty mechanically from the state machine diagrams.
The engine interface has a method for each type of message and each local action. I started out with one method for all messages and another for all local actions, but that turned out to be a bad design - the information about what kind of message was being handled was lost when the message was passed to the engine, and had to be recovered using an instanceof ladder.
Each engine method takes a message or an action and a session, and returns an updated session. A transaction is passed in so the engine can send messages, attach events, and do any other work it needs to do (such as changing the visibility of groups, in the case of this protocol). This removes the need to run tasks outside the engine, so the protocol logic is better encapsulated inside the engine.
Parsing and encoding of messages and sessions is separated from protocol logic. MessageParser, MessageEncoder and the validator are the only classes that know how messages and their metadata are formatted, and likewise SessionParser and SessionEncoder are the only classes that know how sessions are formatted. The metadata keys are declared in a package-private interface.
It's common knowledge that I never make mistakes, so to keep things interesting I've hidden 114 deliberate mistakes in this code. See how many you can spot!
Needs tests before #709 is closed.
See merge request !382
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
Create GroupDissolvedEvent and react to it
This MR also makes the private group list react to incoming group invitations (once they are implemented).
Closes#736, #737
See merge request !392
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
Use contact ID rather than messaging group ID to identify conversation
We originally used the private messaging group ID to identify the private conversation, but now that the conversation includes messages from multiple clients it's more appropriate to use the contact ID.
This refactoring isn't urgent - I've had the branch lying around for a while, but I'm putting it up for review because #734 will touch some of the same code.
See merge request !386
Add unit tests for KeyManagerImpl
This also creates a `TransportKeyManager` interface and a factory for that to be able to test things separately.
Closes#205
See merge request !380
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
Improve QR code workflow slightly
* Improve wording so contacts know they need meet up to scan
and scan each other's codes
* Use consistent progress bar styles
Closes#348
See merge request !381
