[UI] added option to enable alternate chat layout

The user can now enable an IRC stylish chat layout.

Change-Id: I46f024bbe4e6c81a3a9a3a5c2ccb6ae187fb6d9b
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1909
Tested-by: Jenkins CI
Reviewed-by: Stefan Rossbach <srossbach@arcor.de>