Update functions called on key events and from the tool bar
Select multiple nodes with click + ctrl

Changed cmdDeleteNode to cmdDeleteNodes. We now have a list of currentSelectedNodeNames instead of a single node name. We can copy/paste/duplicate multiple nodes at a time.
Modify key events to allow mutiple selection on ctrl + click
Merge branch 'develop' of github.com:buttleofx/ButtleOFX into develop

Conflicts:
	buttleofx/MainWindow.qml
	buttleofx/data/buttleData.py
	buttleofx/manager/nodeManager.py
SetCurrentSelectedNode is not a Slot anymore
Merge branch 'develop' of github.com:buttleofx/ButtleOFX into develop