fix for panicked MCed units
fix for door fix
keep track of units spotted this turn

so we don't stop if we re-spot a unit we've already seen this turn.
un-kneeling as the first step of a walk action (visual fix)
yet more changes in pathfinding

sigh. so much redundancy.
let the isBlocked function take care of pathing through other units.

let the walk state worry about whether or not we can walk to the tile
in question, and charge cost any TUs if you can't.
notify us of chryssalid kills.
make sure dead units can't see a damn thing.
don't keep MCed aliens visible when we shouldn't.
add extra clips to xcom

do a second pass on xcom units and assign them an extra clip, if available.