(MESS) c64 improvement & fix [Alex Jackson]
 * Cache pointers to basic and kernal ROMs at startup (they can be in separate
   ROM regions or a single ROM depending on model) rather than branching on
   every read

 * Moved "ProLogic-DOS Classic" BIOS from c64 to c64c, since it's clearly meant
   for, and only successfully boots on, the latter machine