Make sure all the image-related QObjects belong to the GUI thread
- It is needed to make QTimer work correctly
- It is also needed to make inter-thread (queued) signals work correctly.
What the patch does is basically putting all the KisImage children
into a QObject hierarchy with the root in KisImage. Then, when KisImage
is transferred to another thread, all the children (and timers)
are transferred as well.