[Multitap] Add support for 3+ controller setups

[jonthysell]

There should be another class that supports any of the multi-tap options: the two official Team Player variants and EA's 4Way Play.

There are some detils here about the protocol: https://www.raphnet.net/divers/genesis_multitaps/index_en.php

[csBlueChip]

FYI: https://www.raphnet.net/divers/documentation/genesis_multitap.txt
...nice state table in section 5