Removed unnecessary variable declarations and conditional cases by using an "assume, alternate, verify assumption" pattern and reusing ax0/ay0 when they would never be referenced again.
this is approximately token-neutral but performance-saving. each function parameter makes its call cost worse. When can_move is called inside a loop, we already have a table and we unpack to call can_move; moving the unpack into can_move saves us marshalling cost. It requires us to construct a table in a different spot (where we were not previously doing so) but that spot is not in a loop.
The tug_crate conversion is for performance. `foreach(tbl, predefined_func)` is substantially faster than a standard `for` loop using the `all` iterator. However, if the function inside the foreach is defined inline, it's much slower due to closure-construction overhead (even though nothing is being closed over). Converting `tug_crate` to take a table as an argument allows foreach to feed right into it, and it also naturally suggests a rewrite a few lines down to get rid of duplicative listing of `mx0,my0,dmx,dmy`, saving several tokens.
I'm going to take a look at can_move to see if it's worth making iits mx0,my0,dmx,dmy arguments into a table as well.
