Fix integration tests

First problem was a race condition with message delivery and the second
one due to the fact that we no longer plan to allow adding of additional
blogs, so the test for that has simply been removed.

See merge request !333

Check length of text after spanning

Closes #685

See merge request !334

First problem was a race condition with message delivery and the second
one due to the fact that we no longer plan to allow adding of additional
blogs, so the test for that has simply been removed.

The app _name string is marked as non-translatable and the new_identity_item string no longer exists.

Forum controller thread safety and tree safety

This branch solves the concurrent forum issues by code restructure and refactoring.

Closes #556 
Closes #552 

See merge request !262

Remove toolbar animation to fix the missing toolbar on first start

Closes #644

See merge request !331

Prevent personal blogs from being removed

This also adds unit tests to prevent regressions like this in the future.

Closes #679

See merge request !330

When a message is shared, share its transitive dependencies

Like other recursive operations on the dependency graph, this is
not done in a single transaction to prevent an attacker from creating
arbitrary large transactions.

So at startup, the `ValidationManager` finds and resumes any
unfinished operations, by looking for unshared messages with shared
dependents.

Closes #589

See merge request !325

Like other recursive operations on the dependency graph, this is
not done in a single transaction to prevent an attacker from creating
arbitrary large transactions.

So at startup, the `ValidationManager` finds and resumes any
unfinished operations, by looking for shared messages with unshared
dependencies.

This also adds unit tests to prevent regressions like this in the
future.

Try harder to find suitable camera parameters

This branch fixes QR code scanning on the Galaxy Nexus running Cyanogen Mod 12.1 (Android 5.1.1), without breaking QR code scanning on any of the other test devices.

The problem on the Galaxy Nexus was that the selected scene mode was overriding the selected focus mode, so we asked for continuous picture mode but got macro mode. Macro mode requires startAutoFocus() to be called, but we weren't calling it because we'd asked for continuous picture mode.

The fix for that problem is to query the focus mode after applying the parameters and call startAutoFocus() based on the actual mode rather than the requested mode.

But then I discovered another problem: barcode scene mode was setting the flash to auto, so in low light the flash was turning on and off while trying to scan QR codes. That might work well for printed QR codes, but it's terrible when scanning from a screen.

The fix for the new problem is to select barcode scene mode, then try to disable the flash, and if that fails, reset the scene mode. Then we pick the best available video stabilisation, focus mode and preview size.

On the Galaxy Nexus with CM 12.1, that means we use continuous picture mode instead of barcode scene mode, which works fine. All the other test devices pick the same settings as before.

See merge request !321

Check whether File#listFiles() returns null

The docs say this can happen if there's an I/O error. Also fixed a throw-in-finally-block warning and renamed an IoUtils method to make its contract clearer.

See merge request !328

The docs say this can happen for a directory if there's an I/O error.

Remove base32 TODOs, fix a potential NPE

I thought we'd be able to get higher data density in QR codes by using base32 instead of base64, allowing the QR code to use alphanumeric mode instead of byte mode. But I tried it, and although the QR code does use alphanumeric mode, it comes out at exactly the same size (see the 346-use-base32-for-qr-codes branch). So this MR removes the TODOs and fixes a potential NPE I spotted while working on the other branch.

See merge request !327

Recreate cache directory after deleting app data

This fixes a warning on the Moto G:
```
E/libEGL: error creating cache file /data/data/org.briarproject/cache/com.android.opengl.shaders_cache: No such file or directory (2)
```

@grote might possibly be related to hardware rendering issues.

See merge request !326

Add more introduction tests for fake MAC and modified timestamp

Closes #627, #669

See merge request !315

Add first onboarding screen

When the user enters a private conversation after adding her second
contact, an onboarding screen will be shown highlighting the possibility
of introducing the contacts to each other.

![intro2](/uploads/b2cd4377f39974ca1fbd95649558e487/intro2.gif)

Closes #357

See merge request !324

When the user enters a private conversation after adding her second
contact, an onboarding screen will be shown highlighting the possibility
of introducing the contacts to each other.

Emoji

This MR introduces a custom Emoji implementation to Briar for devices that do not support Emoji sufficiently. It is heavily based on Signal's implementation. Hence, the license for the Android part has been changed to GPLv3.

So far, emoji input is only supported for forums and private conversations that both rely on the same `TextInputView`.

![emoji2](/uploads/f69af031e72efb0bd6f0f67a9574d11f/emoji2.gif)

See merge request !317

Add functionality to save and restore recently used Emojis

Update emoji and add new categories based on AOSP's XML file

Don't offer messages back to the sender

Closes #538

See merge request !323

Avoid repeated author status lookups

Closes #625

See merge request !322

Include stream number in stream header nonce

See the corresponding change in the BTP spec for an explanation:
https://code.briarproject.org/akwizgran/briar-spec/commit/388e1d23c04c2f6954d13d36ffc231611a3c6fa9

Closes #329

See merge request !320