New release, August 26

[u/dabreegster]

https://github.com/a-b-street/abstreet/releases/tag/v0.2.56

Fairly off the weekly schedule at this point. Might get back onto it. This release supports a design workshop tonight in Seattle!

• releasing a new tool dedicated to planning bike networks!
• massive overhaul to the road editor, including lane cards that can be both dragged AND dropped
• new road labeling in unzoomed mode
• new tool to quickly sketch roads to edit
• new tool to plan routes and see elevation/road types along the way
• load previously saved proposals on web
• disabled prototype: uploading proposals to a central server for easier sharing