We had a ton of helper functions in qt-gui.cpp which really didn't make
much sense. So I moved them all into qthelper.cpp.
Also moved the UserAgent helper that didn't belong in the UpdateHandler to
begin with - that's a generic helper used in many places...
With this we can successfully build using cmake again.
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
