Add another path placement method to rmgen lib

[FeXoR]

The two maps Deep Forest and Schwarzwald both use the same path placement method. That method is much more irregular and allows path bended to either side as well as roughly straight paths. So it would be a nice addition to the much more regular existing path placement method in the libs.

This method should be put into the rmgen lib as a function to be then used in both maps.

Schwarzwald should have the ammount of paths changed to one roughly straight one to the lake and one to each naigboring player from each player ... while we're at it ;)