namco23: Spring cleaning, including:
  - remove a bunch of s23 prefixes/suffixes useless since the OOification
  - rename p3d to c435
  - unify c435 dma and pio
  - identify the generic set state command
  - implement the interrupt set state subcommand
  - fix the endianness of the controls port (controls still don't work though)
  - various whatevers                                   [O. Galibert]