[#18678] Swizzle properties for Mathutils.Vector

patch from Alex Fraser (z0r)

eg.
  - vec.xyz = vec.zyx
  - vec.xy = vec.zw
  - vec.xxy = vec.wzz
  - vec.yzyz = vec.yxyx

See http://en.wikipedia.org/wiki/Swizzling_(computer_graphics)

made some minor modifications to this patch.

tested access times and adding 336 attributes to vectors doesn't make a noticeable differences to speed of existing axis attributes (x,y,z,w) - thanks to python dict lookups.

source/blender/python/BPY_interface.c

@@ -286,6 +286,8 @@ void BPY_end_python( void )
 		free_libblock( &G.main->script, script );
 	}
 
+	Mathutils_Free(NULL);
+	
 	Py_Finalize(  );
 
 	BPyMenu_RemoveAllEntries(  );	/* freeing bpymenu mem */