Add Support for the internal 1565 Drive of the MEGA65 R3

[oe3gwu]

It would be nice to have the 1565 Drive working with 1581 or even CMD-FD2000 Disks. This would make my archiving easier quite much. For now the internal disk drive cant be used at all from the core.

It would be nice to have the choice for Disk Drive 8 to use an image (of any format) or the internal 1565 Drive. It is important for quite many software, that it is seens as 1581 or CMD FD-2000 Drive. Because the 1565 was never released from Commodore, this would break software like dracopy or so.