Make data tree creation efficient

[pantierra]

The data = OsmHelper() object initiation queries and creates the whole data structure of all routes and stops already in the constructor.

This is not very efficient, because even when updating only the routes (or even one route) or only the stops, everything get's queried and built anyway.

I guess, we should move those queries and data tree builders into the respective functions, instead of building the whole data tree in the constructor function.

[pantierra]

Fixed with latest merge.