Some methods of JingleVoIPContent have been moved to JingleRTPContent, in prevision of a video content class.

The pipeline now starts in setupStream, and the stream's direction is changed when the stream is ready.

better compliance to the last version of XEP 0166, 0167 and 0176

Also use % formatting instead of string replace.
Translation files updated accordingly.

add account combobox to join groupchat dialog when we try to join a groupchat from another chat / groupchat. Fixes #3344

when a JID is invalid in member / admin / ... list in MUC configuration, just ignore this JID and not all others. Fixes #5241

show only once unread messages at startup when we have twice the same contact in 2 accounts. Fixes #2921

don't move selection when new text arrives and selection goes until the end of conversation textview. Fixes #5223