libinput backend

TODO:

• Establish backend
• Add new types
• Implement container for multiple backends
• Split events.c into several files
• Devices
  • Keyboards
    • Events
    • Key maps
    • LEDs
  • Pointers
    • DRM hardware cursor - implemented but doesn't work, don't know why
  • Touch
    • Get mapped output from udev not among the udev properties on my hardware
  • Tablet tool
  • Tablet pad
  • Gesture will not support
• Device cleanup
• Demos
  • Keyboard
  • Pointer
  • Touch
  • Tablets
• Put more thought into the design

I own hardware for everything, so it's just a matter of writing the code.