OSX Port

[randomPoison]

• [x] Open a window.
• [ ] Create OpenGL context and render to window.
• [ ] Get keyboard input.
  • [ ] Get both scancode and keycode input.
• [x] Get mouse input.
  • [ ] Get mouse input when cursor is outside of window.
• [ ] High frequency timers (microsecond accuracy preferably).
• [ ] Thread sleeping code (1 millisecond accuracy preferably).
• [ ] Low level audio access (at least access to audio drivers, preferably direct access to audio device).
• [ ] Hotloading support.
• [x] Configure CI through Travis.

[randomPoison]

#82 Adds initial support for building on OS X through Travis.