(MESS) gameboy: added dump of Color GameBoy 188 in 1 multicart,
and partially implemented the required mapper [Team Europe, Fabio Priuli]


after selecting a game, the CPU always points to the correct bank of the cart,
but some games don't work anyway (e.g. Duck Tales, PacMan, etc.)
I don't have time to further debug this, at the moment, so I leave it to whoever
wants to take a look