Blender Git Loki

All editable GPencil stroke points are now shown when editing is enabled

The intention of this change is to make it easier to tell when you are in
stroke editing mode.

Notes:
* Even so, it isn't always obvious that these verts are being shown,
especially when the colors of the unselected points match the stoke
color OR when multiple overlapping strokes are drawn in the same place.
* It's also worth noting that pivoting away from the modal workflow again
(even though we've tried the non-modal one, and it was quite a clumsy failure)
is going to start becoming a lot harder.