fix write-protect flag when using F011 emulation registers to write.
writes will now fail to write-protected disk images.
fix f011 EQ flag (was never set)
annotate write sector routine in C65 ROM.
fix name of aclSCLK -> aclSCK.
make PS2 keyboard scan codes available.
begin adding support for RESTORE key triggering NMI on short press
and RESET on long press (>0.5 seconds).
fix reset and nmi from restore key plumbing, and allow switches
14 and 15 to mask NMI and RESET respectively for debugging.
fix keyboard mapping to match keyrah v2 with switch in lower
position.
fix NMI and RESET plumbing for synthesis.
Holding RESTORE for 0.5 - 2 sec generates RESET.
Holding for less generates NMI on release.
Holding for more generates nothing.