Grease Pencil v2 Branch

Improve current Grease Pencil in order to get a better 2D animation tool.

More info in WIKI pages: https://wiki.blender.org/index.php/User:Antoniov

Reviewed By: Severin, aligorith, campbellbarton

Patch by @antoniov, with edits by @Severin.

Differential Revision: https://developer.blender.org/D2115

source/blender/editors/transform/transform_generics.c

@@ -975,7 +975,9 @@ static void recalcData_gpencil_strokes(TransInfo *t)
 	TransData *td = t->data;
 	for (int i = 0; i < t->total; i++, td++) {
 		bGPDstroke *gps = td->extra;
-		gps->flag |= GP_STROKE_RECALC_CACHES;
+		if (gps != NULL) {
+			gps->flag |= GP_STROKE_RECALC_CACHES;
+		}
 	}
 }