[PATCH] Implement move surface key bindings.

[Bill Spitzak]

On cursor images, I believe the interface can be extremely simple. There 
would be only one call, which is "set the cursor for this input device 
to this surface". Attaching new buffers to that surface will change the 
cursor image.

Clients should be expected to set the desired cursor when the pointer 
enters their surfaces. This is much easier for toolkits to handle than 
any kind of "attach a cursor to a surface" api, because it is trivial 
for the toolkit to use the same code for this as for making different 
cursors for the internal parts of it's surfaces, which the compositor 
knows nothing about.

The compositor can perhaps publish a few global surface ids for default 
cursors. It may also want to respond to "dead" clients by changing the 
cursor to the default if the client fails to set it in a reasonable time 
after the entry event.