Blender Git Loki

GPencil Editors API: Added utility function to be called to get Copy-on-Write evaluated copies of data

* Use ED_gpencil_get_active() for writing settings back to the original datablock
(existing callback used in most operators now)

* Use ED_gpencil_get_active_evaluated() for getting the COW-evaluated geometry
(i.e. with modifiers, etc.) applied. i.e.,
``` const bGPdata *gpd_eval = ED_gpencil_get_active_evaluated(C); ```