Blender Git Loki

Fix: Lasso select for Grease Pencil doesn't work in the Nodes Editor

In the nodes editor, Ctrl-LMB-drag is taken by "Cut", and it seems impossible
for any other keymap to override that. Instead, the default lasso select hotkey
there is Ctrl-Alt-LMB-drag instead.

To get Grease Pencil lasso select (in GP Editmode) to work in the Nodes Editor too,
this commit adds the Ctrl-Alt-LMB-drag binding here too. However, to make things easier,
this extra binding will be part of the Grease Pencil keymap everywhere. There doesn't
seem to be any conflicts with having this in place - until we find them, this should
be ok to have.