[SDL] adding wacom tablet support to sdl

[Ryan C. Gordon]

> Anyway, I too am very interested in cross-platform tablet support,
> preferably for SDL, but otherwise too.  I'd be willing to help out with
> at least the Linux side of things.

My understanding is that this is all planned for 1.3, when we start 
focusing on multiple input devices. If it doesn't go into SDL 1.3, it'll 
go into ManyMouse (which is still pretty much spinning until x.org gets 
the next-gen XInput extension worked out).

--ryan.