Briar Headless still lacks web events of delivery state changes, therefore this commit doesn't update delivery states automatically.
There's #69 to do that.

Fixes #52.

Converted with https://gitlab.com/AlessandroLucchet/VectorDrawable2Svg/-/blob/d401706209b26f7be445a15fed1b217164e48802/VectorDrawable2Svg.py

Sources:
* https://code.briarproject.org/briar/briar/-/blob/4e5f2e31df85cb6d56559bb99bc921d322f6a1af/briar-android/src/main/res/drawable/message_delivered.xml
* https://code.briarproject.org/briar/briar/-/blob/4e5f2e31df85cb6d56559bb99bc921d322f6a1af/briar-android/src/main/res/drawable/message_sent.xml
* https://code.briarproject.org/briar/briar/-/blob/4e5f2e31df85cb6d56559bb99bc921d322f6a1af/briar-android/src/main/res/drawable/message_stored.xml

Related to #52.

Now also with removed items from briar-gtk.

This seems to remove old translations from briar-gtk.

This doesn't work, because gettext doesn't pick up the translations.
The context in the source string makes gettext think that it's a special
translation, while our workaround suggests that it has no context.

Transifex offers the option to add context manually.

Those changes aren't yet implemented, but will definitively be included.

Fixes #28.

Fixes #68.

The green now fully shines while I made the full black ring border a
dark grey.

To increase contrast, on suggestion by @grote.

As suggested by LocLab.

Still not working, but we surely need this...

Fixes #67.

On suggestions by yahoe.001 and anm on Transifex.

Credits of those texts go to:
* https://code.briarproject.org/briar/briar/-/blob/4e5f2e31df85cb6d56559bb99bc921d322f6a1af/TRANSLATION.md
* !65 (comment 41992)

Related to #65

Related to #66

Followup to !63