Create custom BriarRecyclerView and use it for the contact list.

It is a common pattern to have a list with an empty view and a progress bar.
This commit introduces a custom BriarRecyclerView and uses it for the
contact list.

No more manually hiding and showing empty views and progress bars is
necessary when using the new BriarRecyclerView instead of RecyclerView.

Please note that this conflicts with !44 at the moment and needs to be
implemented for !36 once merged.

Closes #198

See merge request !45

Overhauled Conversation View with Message Bubbles

The Conversation View now uses a RecyclerView with conversation bubbles
in alternating colors and vector drawables to indicate message state.

The conversation bubbles have been taken from Telegram
and can be replaced by a UX designer later.
There's also a special bubble for unread messages,
so they are not overlooked when they come in delayed.

This commit also addresses #9, because message text can
now be selected and copied. This is done by using

    android:textIsSelectable="true"

which only works for API level 11 or higher.

If we want copy and paste on lower API levels,
additional measures have to be implemented.

See merge request !36

It is a common pattern to have a list with an empty view and a progress bar.
This commit introduces a custom BriarRecyclerView and uses it for the
contact list.

No more manually hiding and showing empty views and progress bars is
necessary when using the new BriarRecyclerView instead of RecyclerView.

Please note that this conflicts with !44 at the moment and needs to be
implemented for !36 once merged.

Closes #198

Add a floating action button (FAB) in the contact list

The button hides itself when you scroll down the list of contacts
and shows again when you scroll up.

To properly color the button, the accent color has been defined.
It uses the same color as the action bar (primary color).
I leave it to a UX designer to adapt the color scheme.

Please note that the design support library was used.
It includes the app-compat library, so this has been removed
from the `build.gradle` file.

Closes #199

See merge request !44

The button hides itself when you scroll down the list of contacts
and shows again when you scroll up.

To properly color the button, the accent color has been defined.
It uses the same color as the action bar (primary color).
I leave it to a UX designer to adapt the color scheme.

Please note that the design support library was used.
It includes the app-compat library, so this has been removed
from the `build.gradle` file.

Closes #199

Do not show green text for enabled transports, use only green icons.

This addresses part of #197 and is a fairly small change.

See merge request !43

This addresses part of #197

Show home screen if user backs out of password activity

This borrows a technique from @grote's crash reporter patch to fix #7. If the user presses the back button in PasswordActivity, the home screen is shown. Previously, pressing the back button removed PasswordActivity from the back stack, causing the next activity in the back stack to spawn another PasswordActivity.


See merge request !41

Use XSalsa20-Poly1305 instead of AES-GCM for transport encryption and password storage.

This patch integrates @str4d's new authenticated cipher implementation. It depends on !18.

See merge request !35

properly notify the view adapter of dataset changes
in order to avoid invalidating the entire dataset when not absolutely necessary.

This change also shows unread messages in a different color,
so users do not fail to notice delayed messages.

It now uses conversation bubbles in alternating colors
and vector drawables to indicate message state.

The conversation bubbles have been taken from Telegram
and can be replaced by a UX designer later.

This commit also addresses #9, because message text can
now be selected and copied. This is done by using

    android:textIsSelectable="true"

which only works for API level 11 or higher.

If we want copy and paste on lower API levels,
additional measures have to be implemented.

Use a RecyclerView for the Contact List

This is the first RecyclerView in the project. I am using a SortedList to keep the contacts sorted by latest activity.

Also, I removed the icon footer and moved the icon into ActionBar. I did the same with the long-press contact deletion action which eventually will move to the new contact details activity.

Several icons have been replaced by vector drawables and all the views are now defined in XML.

See merge request !38

When you receive a message from a contact,
it will be moved to the top of the list with a nice animation.
Also with this commit, not the entire data set is invalidated each time data changes,
but only the parts of the data that really require an update.

Furthermore, the ContactListItemComparator that is not needed anymore is
removed.

Inject dbExecutor as ExecutorService

Closes #188, despite the branch name. :0)

See merge request !33

Small Improvements for Crash Handling Activities

This relates to #7 and closes #193

See merge request !37

Fix off-by-one error in key rotation

Fixes #190.

See merge request !32

Put labels below transport icons

This prevents the labels from wrapping on small screens. Fixes #191.

See merge request !34

Update dashboard icons when resuming activity.

Fixes #186. 

The issue is that DashboardActivity doesn't receive events while it's paused. This appears to be device-dependent because it depends on the relative speed of resuming the activity vs delivering the event. If the activity resumes quickly enough, it will register its event listener and catch the event. If not, it won't update its icons until it's recreated, e.g. by rotating the screen.

See merge request !31

Switch KDF from SHA-256 to Blake2. #169

The BTP spec calls for Blake2s, but there's no Java implementation available. I suggest we go with Blake2b for now. If it turns out to be a performance bottleneck on 32-bit platforms we can consider implementing Blake2s and merging it upstream.

This depends on !13.

See merge request !21

Stream encryption for BTP version 2. #111

This patch implements the stream header from the BTPv2 spec (https://code.briarproject.org/akwizgran/briar/wikis/BTP).

This merge request depends on !13.

See merge request !18