Makefile: add install target

Install target is usefull to install in system default executable directory.
InputController: 360 controller compatibility

Direction pad of the 360 controller was not working because SDL detect it as an
hat. I just added SDL_JOYHATMOTION management.
Packaging: add debian packaging.

dppkg-buildpackage now creates a debian package wich contains snes9x and
confTool executable files. They will be installed in /usr/bin directory.
Merge branch '360-controller'

* 360-controller:
  InputController: 360 controller compatibility
Update changelog for 0.3 release