Dynamic track and TDBTraveller coorination: (1) Common methods for interpolation along straight and curved sections; (2) dynamic track subsections decomposed into up to five independent sections. These changes fix elevation discrepancies between dynamic track and travelers for large-angle curves.
git-svn-id: http://svn.uktrainsim.com/svn/openrails/trunk@163 a9f3cfff-6c41-7446-b0ca-052bd761e6eb