Fixed issues surrounding the increased vertex limit:

* Created a MESH_MAX_VERTS macro in DNA_mesh_types.h
* fixed vert limit for converting displistmesh ==> mesh
* fixed vert limit when doing boolean operations

source/blender/src/editobject.c

@@ -1070,7 +1070,7 @@ void exit_editmode(int freedata)	/* freedata==0 at render */
 		/* temporal */
 		countall();
 
-		if(G.totvert>2000000000L) {
+		if(G.totvert>MESH_MAX_VERTS) {
 			error("too many vertices");
 			return;
 		}