gui: import 0.12.x configuration of group tabs

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: simplify ungroupped tab logic

We have some problems with group from gtalk accounts. I do not want to
dive into this, so I just get the simplest acceptable solution.

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: fix refreshing group filter when updating group tab

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: update translations of group tab bar

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: #2621 fixed: lots of Ungroupped tabs could appear in Group Tab Bar

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>