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.
Attach optional messages to invitations in Conversation view

Closes#359
See merge request !299
When we clear a list in onPause(), the proper behavior is that the empty state
message is shown, because the list is indeed empty.
However, we will reload the list content again in onResume(),
so the fix chosen in this commit is to force showing the progress bar
right after clearing the list.
Closes#576
This prevents trying to access the same group metadata in different groups.
Also, the conversation does not need to be reloaded once introduction messages arrive.
Closes#535
Show all Forum Invitations, not only the first one to prevent cut-offs and forks
This MR solves the problems outlined in #461 by always showing forum invitations, even if the user already subscribed to the forum.
Available Forums have been renamed to Forum Invitations in the UI:


Closes#461
See merge request !241
Simple Empty State Messages
This MR implements very basic and simple empty state messages for the
current features.
This is how it looks (note that the contact add FAB will be removed soon):




Closes#327
See merge request !236
Fixing fragment instance restore
Alas, it turns out that my neat way of integrating the Fragments into the dependency graph was not without problems. Me and @grote discovered that this presented us with a lot of problems on orientation changes as the Activity is re-created, and therefore parts of the dependency graph. The simplest solution was simply to abandon the idea, i.e. with this branch Fragments are no longer part of the dependency graph.
See merge request !215
This adds a new table to the database to hold message dependencies.
It introduces two more message states: pending and delivered
The valid column in the database was renamed to state to better reflect
its new extended meaning.
The DatabaseComponent was extended with three methods for:
* adding dependencies
* getting dependencies of a message
* getting messages that depend on a message (dependents)
* getting messages to be delivered (by startup hook)
* getting pending messages to be possibly delivered (by startup hook)
In order to reflect the new states, things that were previously true for
VALID messages have been changed to now be true for DELIVERED messages.
Since pending messages should not be available to clients, many database
queries have been modified to only return results for delivered
messages.
All added methods and changes should come with updated unit tests.
Please note that the database version was bumped in this commit.
The new activity shows who you are sharing a forum with and who shares a
forum with you. It is accessible from the overflow menu when in a forum.
Closes#398
Forum Sharing Client UI
This changes `ShareForumActivity` to use two fragments to facilitate
forum sharing with the new Forum Sharing Client backend.
The `ContactSelectorFragment` allows the user to select a
number of contacts. If there is an ongoing sharing session or the forum
is already shared with the contact, it is disabled in the list. If there
is at least one contact selected, a button appears in the toolbar that
brings the user to the `ShareForumMessageFragment` where the user can
write an optional message to be send along with the invitation.
After sending an invitation, the user is brought back to the forum that
she shared and there is a snackbar showing up briefly to indicate the
successful invitation.
The invitation is shown along with the message within the private
conversation of each contact. The person who shares the forum also sees
the invitation and the message as outgoing messages that also display
the current status of the messages.
A notification is shown like for other private messages as well.
Please note that this commit does not include a way for users to respond
to invitations. This is in MR !172. Both MRs are based on the new backend in !170.


See merge request !171
This changes `ShareForumActivity` to use two fragments to facilitate
forum sharing with the new Forum Sharing Client backend.
The `ContactSelectorFragment` allows the user to select a
number of contacts. If there is an ongoing sharing session or the forum
is already shared with the contact, it is disabled in the list. If there
is at least one contact selected, a button appears in the toolbar that
brings the user to the `ShareForumMessageFragment` where the user can
write an optional message to be send along with the invitation.
After sending an invitation, the user is brought back to the forum that
she shared and there is a snackbar showing up briefly to indicate the
successful invitation.
The invitation is shown along with the message within the private
conversation of each contact. The person who shares the forum also sees
the invitation and the message as outgoing messages that also display
the current status of the messages.
A notification is shown like for other private messages as well.
Please note that this commit does not include a way for users to respond
to invitations.
Turn list of available forums into a BriarRecyclerView with XML layout.
Allow to respond to forum invitations from the list of available forums.
The user can either accept or decline an invitation.
This commit replaces the old ForumSharingManagerImpl with a new one
which is based on state machines and the ProtocolEngine.
There is a SharerEngine and a InviteeEngine that take care of state
transitions, messages, events and trigger actions to be carried out by
the ForumSharingManagerImpl. This is all very similar to the
Introduction Client.
The general sharing paradigm has been changed from sharing as a state to
sharing as an action. Now the UI can allow users to invite contacts to
forums. The contacts can accept or decline the invitiation. Also, the
Forum Sharing Manger is notified when users leave a forum.
Closes#322
Methods for creating, adding and removing forums have been moved to the
`ForumManager`. In order to still handle removing forums properly, a
`RemoveForumHook` has been introduced.
Methods for sharing forums with all current and future contacts have
been removed along with the localGroup where this information was saved.
The `ShareForumActivity` now has the proper label.
The `SessionId` and the `ProtocolEngine` have been moved to the
`clients` package.
This addresses part of #322 and part of what has been discussed in #320.
This commit is a small change that replaces the custom UI elements in
the forum list with a Snackbar and an Toolbar menu.
Addresses one part (2b) of #305
This commit introduces an abstract `BaseContactListAdapter` which provides
most of the adapter logic. The original `ContactListAdapter` extends it to
show date and online status of the contacts.
The new `ContactChooserAdapter` which is used for introductions extends
the `ContactListAdapter` and adds logic for graying out contacts from
different identities than the currently used one.
A new `ContactSelectorAdapter` extends the `BaseContactListAdapter` and
allows to select multiple contacts. It offers a method to return a
collection of all selected `ContactId`s.
This commit also sneaks in an animation when the 'Share Forum' button
is clicked.
Closes#292
Use consistent styling for dialogs. #296
Converted all dialogs to use the support library and the Briar theme, so they have a consistent Material Design appearance across all Android versions.
See merge request !152