**Breaking change**
Removed the `JOY_SNES_*` and `JOY_SEGA_*` constants. Imho there's no reason for a modern game engine to provide button aliases for decades-old hardware.
Also renamed `JOY_ANALOG_{0,1}_{X,Y}` to `JOY_ANALOG_{L,R}{X,Y}` and removed `JOY_ANALOG_2_*`.