[Freeciv-Dev] (PR#4530) rewrite rails/roads code

["Jason Short" <jdorje@xxxxxxxxxxxxxxxxxxxxx>]

The attached patch is a major cleanup to the road/rail drawing code.  It
separates the logic (when to draw roads/rails in which direction) from
the drawing code (which differs between tileset roadstyles).  Overall
the code becomes much shorter (~50 lines, 1200 bytes are cut out), and
several bugs are fixed.

draw_diagonal_roads now works completely.  Also when draw_cities is off,
isolated roads/rails will correctly be drawn on city tiles.

When it comes time to implement roadstyle 2 (civ3 style of roads), it
will be easier because the logic and drawing are separated.

This supercedes PR#2603.

jason

roads_rails.diff
Description: roads_rails.diff