#37 "Close enough" move order execution

[Nigel Phillips]

Units do not regard a move order as finished until they
have arrived at the exact spot specified. But, they
often cannot get to the exact spot because someone else
is there. What is needed is for them to know it's ok to
sleep/drop that order if they're as close as they need
be. Otherwise this messes up accumulated orders (try
moving a large group about with order accumulation -
doh!).

The fix may involve checking where the other subjects
of the order are, but then what to do if some other
unit occupies the spot?