* add a checkbutton to use the entered nickname by default without asking anymore. Fixes #5141

don't remove occupant from room roster when we try to change our nick to the occupant's nick. Fixes #5120

* fixed some problems with SQL escapement for roster versioning. For example when we have double quote or another character like this. Fixes #5159
* some code refactoring for roster versioning in common/logger.py
* added a docstring and some comments in common/logger.py

restore metacontct correctly when we connect to server and we already have contacts in roster (stored locally). Fixes #5156

* fixed a bug when we remove a contact from our contact list (before we did not remove contact from roster_group table)

* now there is no more sparkling when we update the RosterWindow with the roster received from the server (when server does not handle roster versioning or when it resends the whole roster)

* In order to allow the viewing of the roster when we are offline (and some other cool stuffs), with and without roster versioning, now we load roster when RosterWindow is created (at gajim startup). Fixes #3190