port more asm and funs in sd and vw*

- remove _MUSE_ ifdefs, won't ever be using that... I think
- add stubs for in/out functions
- deal with most of sd stuff, most asm is done, but since neither i/o nor
  timers or interrupts work, it's just a huge nop; timing hacks in particular
- EGA VW_SetScreenmove; "ported" stuff from vw{c,e} in vwa until #if mess
  sorted

lots of pointers are being castrated, must deal with this soon.
remove KEEN and KEEN6 defs and dependent code