Blender Git Loki

Changes for masks API

Made it more consistent with blender convensions
and now it's very familiar to curve's python api.

- Made it spline.points.add(count) wich is more
efficient in cases lots of points are adding.
(points.new was removed tho).

- Removed mask_layer.splines.add(), now it's only
mask_layer.splines.new(), which is how splines
are adding for curves.