[mkgmap-dev] [PATCH v1] Remove one direction of motorways in overview

Attached patch gives a little try how we could remove the duplicate motorways in the overview map. Usually both directions of a motorway are painted on each other. The patch removes all motorway segments from the overview map that span an angle 0° to 180° between first and last point of a segment. It should not be commited because I think we could do better with a specialized filter (?) but it's an easy prototype to check if it's worthy to start such an implementation. WanMil