#5101: Added classes for group objects
#5161: calling tool on link was fixed
#5102: Added support for scene to draw group objects
Merge remote-tracking branch 'origin/devel' into 5081_groups

Conflicts:
	src/visual/ObjectVisualCreator.h
#5103: Added simple tests

- for model simple stuff
- for group stuff
#5197: Interface for creating group objects was created
Merge branch '5081_groups' of https://github.com/OSLL/sca into 5081_groups
#5198: Logic transfered from IScaMimeDataProcessor to ObjectCreator
#5102: Scene now better reacts on groups

- changed flags from isShownRole to isVisibleRole/onSceneRole to
show/hide objects on scene (so that grouped objects still stay in
memory, just hidden) and to detect if they should be added to scene at
all.
#5103: Improved tests for simple stuff

- Now they check if position is correct also
- Check if visibility is correct of old objects and group
#5203: test for GraphFilter was added
#5104: UI for adding groups + scene works normal.

+ some code improvements
+ following bugfixes for branch 5081_groups
Merge remote-tracking branch 'origin/5081_groups' into devel

Conflicts:
	src/widgets/GraphView.cpp