[FEATURE] Snap roads and features to 90°

[mattdm]

Is your feature request related to a problem? Please describe.

This is related to #97, and probably also to #102. As the issue about map rotation notes, many cities are not aligned to the compass points. However, it's even messier than that -- many older cities have sections with different overall alignments, or maybe even no plan at all. This results in a lot of jagged roads no matter the overall rotation.

Describe the solution you'd likeF

Roads which are some amount skewed from alignment should be snapped to that alignment. That is, if a road runs at 93°, alter it to run at 90° instead.

There might be two configurable options:

1. snap if difference is less than N°
2. snap to
   • 90° alignments only
   • also include 45°f diagonals
   • snap to closest 15°

Additional context

I know this is a lot more complicated than the current approach!