Split code into modules

[retep998]

Currently lib.rs is a massive file which makes editing difficult, and can bring certain editors to a crawl.

• Move code from each header into separate module
• Split libraries into separate crates
• Get rid of ugly :: everywhere as soon as glob imports aren't broken.

[retep998]

A design plan has been figured out which doesn't depend on recursive imports. However once recursive imports work correctly the code can be cleaned up.
cc rust-lang/rust#4865
cc rust-lang/rfcs#889

[retep998]

Glob imports will be working correctly in Rust 1.4, so hopefully next year I can begin the transition.

[Eh2406]

What are the next steps, now that we are well past 1.4?

[retep998]

First I stop procrastinating and land the various PRs that are hanging around in limbo. Then once I'm caught up I experiment with removing :: everywhere.

[retep998]

Actually I think I'd like to move things further into submodules based on the subfolder names so it would be winapi::um::d3d11 for example instead of just winapi::d3d11. This might break any code that refers to the submodules explicitly so I'll probably have to wait for winapi 0.3 for this change.

[retep998]

Replaced by #316