This allows the raw offset to be visible inside that for-loop, which will be needed for calling the directionfn for directional neighbours to determine if they can flow in the given direction.
The "new flow logic" name was supposed to indicate that it was a continuation of the old branch by the same name, but it is beginning to become clear that it's not "new" any more and it might lead to confusion with "classic mode" flow logic while that still co-exists.
Explicitly name the subdirectory "pressure logic" to give a better idea of what goes in it, init.lua edited accordingly.
