Haskell FreeType binding

Copperbox revision 413.

I've changed some of the interface to be more like the Haskell OpenGL binding - libraryVersion is now a gettable State Var, and rather than exposing the allocator and deallocator for the ft_library I've wrapped both in a withFreeType call which is like the withNURBSObj function.

Currently this is just an experiment, as I've just looked at a couple of examples where the GL idioms would work well. It would be nice for me if I could adopt HsOpenGL's idioms wholesale - then I wouldn't have to think up abstractions over FreeType for myself. But the GL idioms might not work well for FreeType. OpenGL is a rather special library, the API is essentially a set of commands - very little shared state is transmitted between the client and the library (the NURBS interface is one of the few places where a handle is taken by the client to point to the library's data). FreeType uses many more handles and data is more frequently created by the client and communicated to the library.