remove bigwall hack

it's causing problems in TFTD, easier to patch the offending MCD
fix large unit placement error in atlantis
add bigwall type 9

probably needs some more adjustment, but this takes care of the pathfinding
at minimum
some adjustments to MCDPatches

stopLOS values and footstep sounds, sound -1 for "ignore and use floor"
only do bigwall checking if checking objects
Merge remote-tracking branch 'upstream/master'