Bugfix #6053

When in sculptmode, enter editmode, add faces or vertices, exit editmode,
then undos/redos screw up mesh.

Now the stack for sculpt is freed. Later on one could precisely test why
this undo isn't resistant to such changes.

source/blender/src/editobject.c

@@ -1696,6 +1696,9 @@ void exit_editmode(int flag)	/* freedata==0 at render, 1= freedata, 2= do undo b
 			allqueue(REDRAWIMAGE, 0);
 		if(G.f & G_WEIGHTPAINT)
 			mesh_octree_table(G.obedit, NULL, 'e');
+		/* to be sure, adding/removing data crashes undo for sculpt (ton) */
+		if(G.f & G_SCULPTMODE)
+			sculptmode_undo_free(G.scene);
 	}
 	else if (G.obedit->type==OB_ARMATURE){	
 		load_editArmature();