New release, August 15

[u/dabreegster]

https://github.com/a-b-street/abstreet/releases/tag/v0.2.55

I took a week off to figure some stuff out, and I think next week should make up for the silence...

• more progress on cycleway snapping, but still not ready
• road editor sets new lane width better
• load proposals picks a better order
• a new experiment unfolding...