[crossfire] New arch dir for roads, paths, etc?

[Kevin Bulgrien]

Does anyone have a particular objection to a factoring out of road/path arches
from the wall directory?  I find the association of walls with paths to be
unhelpful if not actually bewildering.  Wall is the last place I look for
roads.

This involves moving dirtroad, paved, footpath, yellow.

It could also involve a move of footbridge and stonebridge from "construct".

Bridge and drawbridge could move too, but as they are in the gwall set, so
probably they are not that important to move.

"travel" or "path" seem like reasonable folder names, though suggestions wil
be entertained. 

Kevin