browser_side: added the flag REUSE_EXISTING_LIBERVIA_WIDGETS - do not create a new chat panel for contacts/groups if a similar one is found in the same tab - this goes with a modification of the methods to create new panels, especially arguments handling - improvement of the accepted groups list for MicroblogPanel (remove duplicates and keep sorted) Details for the new flag: # Set to true to not create a new LiberviaWidget when a similar one # already exist (i.e. a chat panel with the same target). Instead # the existing widget will be eventually removed from its parent # and added to new WidgetsPanel, or replaced to the expected # position if the previous and the new parent are the same.