Land threading.

The whole Calligra application, means Words, runs
in an own thread now. That means the UI is 100%
non-blocking now independent of whatever the
application itself does during loading, layouting,
rendering, ...

While that works well on Android and X11 there
are still some corner-cases left that can or
could result in race-conditions / crashers. Going
to solve them in the next step and also may
give hellgrind a try before turning that into
the next Coffice release.