small pt related GUI issues

[behrisch]

• [ ] I do not find the purple color intuitive for combined rail / street. Could we maybe just invert the rail pattern here (white on black)?
• [ ] train stops show a T but the context menu still says busStop

[namdre]

with an inverted pattern it is harder to distinguish whether we have a shared lane or two independent edges drawn on top of each other (which so often occurs for OSM imports). Since there are no railway sleepers on shared lanes in reality, how about we draw only the rails in purple/cyan on top of the road? The color would unambiguously distinguish it from distinct-roads-on-top-of-each-other and the rails would make the meaning a bit more obvious.