Graphhopper: Support multiple profiles if pt enabled

[karussell]

Currently we support public transit (pt) or road network based FlagEncoder like car. It should be possible to specify graph.flag_encoders=pt,car and being able to route through car or pt. And for the other encoders all speed up algorithms should be available, so nothing complex like multi modal. Just reusing the graph data structure.

As a start we should throw an exception telling that "pt,car" is not yet supported.

[constantin42]

what is the status of the problem, I need the feature for a project. could you please implement this.

[michaz]

Meanwhile, this works.
Enable PT by gtfs.file=.... (Currently) don't mention pt anywhere in flag_encoders or profiles, it'll just work.

[karussell]

Ah, this is great, thanks!