- added new dialog class for special About Dialog (derived from old
AboutDialog, removed unneeded code)
- dialog messages updated
- changed license to EPL 2.0
- changes after review

Change-Id: I03b19821506537f51cd3ccbd6d82dc2604b3d8af
Signed-off-by: Ralf Heydenreich <rheydenr@justmail.de>