Joystick support

This pull request adds generic joystick support. While it's aimed at GCW Zero, I made it so it will work on any platform (other than GP2X/Wiz) where at least 1 joystick device is present.
The features added are:
* Joystick analog support
* Joystick hat support
* Joystick buttons support (with hardcoded actions for now)

Additionally there is a small typo fix for Makefile.gcw0.