* allow duplication of one node/all nodes following a node
* actions available from Node contextual menu and Alt+Click on node for multi-nodes duplication
* add TextField to filter node types by text
* node can be created by pressing enter/return when highlighted
* give active focus to selected node
* node can be deleted when selected by pressing Delete key
* expose node types model as context property
* right clicking on an empty space inside the Graph Editor opens Node Creation menu with all available node types