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.
This will allow any activity to show the expiry warning and password
prompt, and to start and stop BriarService.
SplashScreenActivity, SetupActivity, ExpiryActivity and PasswordActivity
are special cases.
Dev task #52. Known but unverified identities are also supported, but
currently unused. These will be used in future for contacts who've been
introduced but not verified face to face.
If the schema of the database is incompatible with the schema expected
by the code, the database throws a DbSchemaException. LifecycleManager
indicates the error to BriarService, which uses HomeScreenActivity to
show a notification and quit the app.
