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/render/extern/include/RE_pipeline.h

@@ -238,6 +238,9 @@ void RE_render_result_rect_from_ibuf(
 struct RenderLayer *RE_GetRenderLayer(struct RenderResult *rr, const char *name);
 float *RE_RenderLayerGetPass(volatile struct RenderLayer *rl, int passtype, const char *viewname);
 
+/* add passes for grease pencil */
+struct RenderPass *RE_create_gp_pass(struct RenderResult *rr, const char *layername, const char *viewname);
+
 /* obligatory initialize call, disprect is optional */
 void RE_InitState(struct Render *re, struct Render *source, struct RenderData *rd,
                   struct SceneRenderLayer *srl,