Blender Git Loki

GP Add Primitive Ops: Remove the "avoid fast double clicks" event hack

This was making the operator unnecessarily clumsy to use, especially
for anyone used to the way that drawing tools everywhere else work.

Old workflow (with the hack):
1) Click Rectangle/Circle to start the operator
2) Click (Press & Release) in the 3D view to start drawing the shape
3) Click again (Press & Release) to stop drawing
(4) Click again, realising that you forgot to release the mouse in step 2
(provided you realised why it "wasn't working")

New workflow (more in line with standard workflows):
1) Click Rectangle/Circle to start the operator
2) Press and drag in the 3D view to start drawing the shape
3) Release to stop drawing