integrate signals reader into osm reader

[kainagel]

The osm-network reader which respects signals is the last network reader which depends on the old xml-reader. Changing it to the pbf version would complete the osm-contrib for now.

• It seems like the singal stuff needs the osm-reader to be inheritable (non final) (janek)
• Pass Osm-Parser to Osm-Reader from Builder (janek)
• Make Builder inheritable (janek)
• create skeleton implementation of signals reader (janek)
• create unit tests as spec (söhnke)
• finalize implementation (söhnke)
• add integration test (söhnke)

[Janekdererste]

@tthunig is this still in progress?

[tthunig]

Yes, it is. The implementation is done. Söhnke is working on the tests. Then we need to pull in the master...