Merge pull request #45 from bvssvni/master

Removed gfx
Change dependency repo rust-event -> event
Merge pull request #46 from maxsnew/rename_event

Change dependency repo rust-event -> event
Move Window.get_size into WindowGLFW implementation

Depending on the default trait implementation was insufficient as the trait used the size the window was constructed with, which is wrong if the window has ever changed size.
Merge pull request #47 from jakerr/get-size

Move Window.get_size into WindowGLFW implementation
Renamed to glfw_window

Closes https://github.com/PistonDevelopers/glfw_game_window/issues/50