Update to glutin 0.9.0

[willglynn]

glutin 0.9.0 was recently released, which includes an API change that splits the concept of "window" and "GL context" into two separate concepts (rust-windowing/glutin#901) with two separate builders. Other relevant changes include:

• Introducing glutin::GlWindow (which is what we want here),
• Plumbing down device_id on various input events (which are all summarily discarded),
• Changing the window event enums to structs instead of tuples (which is what probably prompted that change),
• Switching cursor positions to f64 (which are summarily reduced to i32 in most cases), and
• Introducing an event loop proxy which can interrupt the event loop, rather than requiring multiple references to the event loop itself.

glutin 0.9.0 also bumps winit to 0.7, which has some significant internal changes on Windows (rust-windowing/winit#209) and MacOS X (rust-windowing/winit#210).

[mitchmindtree]

Looks good!

[bvssvni]

Nice! Merging.