Initial commit implementing ItemView with OpenSceneGraph
Remove Qt3D leftovers
Clean up axis arrows creation code
Cleaned up unsupported features, added camera and trajectory support
Delete window tab when window is closed.
Removed Axis.qml and ModelControls.qml
Disable debug output from ItemView.cpp by default
Set CppOwnership when returning Scenegraph from ItemView
Fixed segfault when closing arstudio with a window open
Fixed segfault when enabling a sequence while processing.

Lock Scenegraph::m_frames with a mutex.
Fixed multiple threading bugs.

Fixed segfault if closing program while processing video.
Removing Scenegraph from ScenegraphAgregator when ItemView is deleted.
travis.yml: install OpenSceneGraph
travis.yml: try enabling GCC builds
MouseArea no longer needed in WindowHandler
Revert "Repository should work without the append_node_ signal/slot."

This reverts commit 13b70137ab1e148bab4f8b55ef176d80e5b40ea4.
Implement a cleaner way to quit while still processing
Show spheres along camera path, some light adjustment
Added basic Bitmap support in ItemView
WindowHandler position fix and ItemView improvement.

Added default case to Sequence type switch.
New ItemView windows appear right to the arstudio window.
Appearing of Windows in WindowHandler modified.

Window appears right or left to the arstudio depending on place where
main window is situated.