Z80: add reset function
IOPORTS: change key for start
STATE: initial implementation of save states (Genecyst format)
Readd resizable flag
Switch back to NTSC timing
CARTIDGE: Implement 16-bit access to backup RAM
CARTIDGE: Implement region '8' as 'E'.
Switch to mem_err for unhandle io writes
Handle cartidges with both backup RAM and bankswitch