3D Viewport rendering (Blender Internal)

Added incremental re-render on view changes. That means all data preprocessing
only needs to be done once on view changes, quite faster that way.

Also fixed a bug in raytracing strands with soft shadows, was wrongly changing
coordinates in a static array.

Note: proper signals for re-renders is still on the todo. Many button options
don't signal a re-render yet. Work around: press G+ESC for quick full renders.

source/blender/render/intern/include/renderdatabase.h

@@ -140,6 +140,9 @@ struct VlakRen *RE_vlakren_copy(struct ObjectRen *obr, struct VlakRen *vlr);
 
 void RE_set_customdata_names(struct ObjectRen *obr, struct CustomData *data);
 
+void area_lamp_vectors(struct LampRen *lar);
+
+
 /* haloren->type: flags */
 #define HA_ONLYSKY		1
 #define HA_VECT			2