Add Additional Layers

[artemis-beta]

There is more of a super issue in that the layer potential is high:

• [x] Signals (base style - i.e. all same image) railway=signal
• [x] Level Crossings railway=level_crossing
• [x] Mainline railways railway=rail (black)
• [x] Tramways railway=tram (blue)
• [ ] Light Rail railway=light_rail (?)
• [ ] Subways railway=subway (?)
• [x] Preserved railways (less frequently used) railway=preserved (brown)
• [ ] Narrow Gauge railways railway=narrow_gauge (orange)
• [x] Stations railway=station
• [x] Tram Stops railway=tram_stop

[Daniel-Gill]

Added pull request for railway=rail https://github.com/artemis-beta/OpenRailChart/pull/14

Once this has been merged and made a bit neater, then it should be a good base for the other polylines: trams, light rail, ect.

[Daniel-Gill]

May be worth considering setting light rail to blue to match tram.

On the Metrolink in OSM, tram/light rail seems to have been used together.

[artemis-beta]

I think tagging issues are not really worth worrying about, nothing much can be done about that