Quite a large one this time... but now we have:

Edges in Mesh
- adds automatic when you use creases. For other situations; call the
  void make_edges(Mesh *me) in mesh.c. Of course, once in editmode the
  edges are automatically recreated.
- in F9 buttons you can add/remove edges too
- both for Mesh and DisplistMesh, so it speeds up drawing quite some in
  wireframe
- render for edges can't work... edges have no material nor tface nor col..
  so here still the faces are rendered in wire

Creases in Subsurf
- based on the code by Chris McFarlen
- main changes is that now edges are used, saving quite some data in file
- use SHIFT+E in editmode to set edges-sharpness. values go from 0-1
- in F9 buttons you can set draw-crease mode. It draws now blended from
  wire color to edge-select color (as provided in Theme)

Known issue: setting sharpness on 1 cube (subdiv 2) gives weird results
with some values... Chris, can you check?

Further; code cleanups, changing 0 in NULL when needed, no warnings, etc etc

source/blender/src/drawmesh.c

@@ -392,7 +392,7 @@ int set_tpage(TFace *tface)
 			printf("name: %d, tpx: %d\n", *bind, tpx);
 			printf("tile: %d, mode: %d\n", fCurtile, tilemode);
 			if (error)
-				printf("error: %d\n", error);
+				printf("error: %d\n", (int)error);
 		}
 		glBindTexture( GL_TEXTURE_2D, *bind);