namcos23.cpp: Start on completing I/O configs for some games.

[Hydreigon223]

• Properly mapped H8 ADC ports to namcos23.cpp
• Added complete input configs for rapidrvr, finfurl, downhill, timecrs2 and 500gp. All these games can coin up and have working analog ports (be sure to calibrate them in service mode).
• Added placeholder I/O ports for the default 's23' input port config. It's roughly translated from previous input port configs. Games using this should coin up the day they properly reach attract mode.
• Added a hacked H8 I/O firmware that replaces the JVS ID with that used in an FCA pcb for 500gp and aking (though 500gp doesn't need it). aking can properly go past its second I/O check only to shortly freeze afterward (anyone against this? please let me know.).
• Changed machine configs to reflect current changes.
• Updated TODO.

[Hydreigon223]

Was stumped in figuring why motoxgo's inputs won't respond at all until I narrowed the issue down to the CPU board. It may come down to mcuen_w, sub_comm_r and/or sub_comm_w and don't have the tools to figure the root issue. Actually no, it comes down to the fact motoxgo handles its JVS differently from other games mainly because it uses two boards in a chain. Did additional testing on one of my cabs to see what happens if certain areas of the main io and exio boards were disconnected.

[Tafoid]

@Hydreigon223 As of this writing you have not sent in the data added to source from this commit for confirmation.
Please send this to the Appropriate Email listed in the link.
Thanks!

500 GP (US, 5GP3 Ver. C) [folder: 500gp - size: 123mb]
missing rom: asc3_io-c1.ic14 [size: 131072] [CRC32: b6627a0e] [SHA1: 92343d527f4a62773c4495b9a04e7e16b9d6fb96]

Angler King (Japan, AG1 Ver. A) [folder: aking - size: 123mb]
missing rom: asc3_io-c1.ic14 [size: 131072] [CRC32: b6627a0e] [SHA1: 92343d527f4a62773c4495b9a04e7e16b9d6fb96]