Switcher sign and pathfinding support + configuration format change
This update makes it possible to place switcher signs above or below tc-hangrail rails, and switch the track invisibly. This allows tc-hangrail to be used with traincarts' path finding API.
Minor change in the configuration file format, so that it uses yaml node list syntax instead of the odd 1: and 2: thing. Older configuration formats remain supported as well.