Don't change icons for thinner versions

See merge request briar/briar!1740

This reverts commit 65509137

First integration test for mailbox with two contacts

See merge request briar/briar!1725

This reverts commit dab8d731

Update Play Store translations and config

See merge request briar/briar!1739

Execute Transifex for fastlane metadata from correct directory

See merge request briar/briar!1738

 by checking, after adding the contact to the mailbox but before creating the message, that the first file containing the mailbox update gets uploaded. Then after creating the message, the second file should be uploaded.

Update instructions on how to build and run briar-headless

Closes #2370

See merge request briar/briar!1726

Use transport properties instead of sending private messages

Remove jcenter repository from gradle files

See merge request briar/briar!1736

Merge redundant strings

See merge request briar/briar!1737

Add hints that both users need to scan each other's QR codes/add each other's links

See merge request briar/briar!1734

Prevent crash in TestDataCreator if blogs or forums are not enabled in core

Closes briar-desktop#420

See merge request briar/briar!1735

Illustration revamp

See merge request briar/briar!1722

Send ClientVersionUpdatedEvent for each client state change, not only on version updates

See merge request briar/briar!1724

in order to avoid two splash screens from being shown.