Fix for bug #3802: Display problems with modifiers and uv face select

The bug reported here was already fixed some weeks ago, but there were
more issues. Modifier display in face select and paint modes was never
properly finished.

This fixes some small drawing update glitches, and only allows modifiers
that preserve a mapping to the original mesh to be applied. Otherwise
selection and painting isn't even possible.

source/blender/include/BDR_editface.h

@@ -53,6 +53,7 @@ void face_select(void);
 void face_borderselect(void);
 void uv_autocalc_tface(void);
 void set_faceselect(void);
+void set_texturepaint(void);
 void face_draw(void);
 void get_same_uv(void);  
 void seam_mark_clear_tface(short mode);