Import inputSwitch node from 2.79 to 2.80

Created by: DolphinDream

The port seem to work except the macro connections or auto connection to VD node. I'm not sure if there is something missing a the socket / node_tree level, or whether there is something not quite working with the VD node.

The anomalous behavior I notice:

1. right click to connect to VD creates the VD node but it doesn't connect the sockets to it
2. the sw macros work except the connection to the VD node (e.g. sw123 only connects V and E but not P socket).
3. once connecting the outputs of the switch node to the vD node the viewport doesn't draw anyting unless i change the frame.

• Code changes complete.
• Code documentation complete.
• Documentation for users complete (or not required, if user never sees these changes).
• Manual testing done.
• Unit-tests implemented.
• Ready for merge.