Add radial grids

[Notgnoshi]

Closes #172
Closes #178

Intended use is for a more interesting grid for use in asemic writing.

• (deferred to Add tool to simplify geometries #6 and Add denisfy tool #179) Add simplify (and densify) tool
• (deferred to Add arbitrary nonlinear rhai transforms #180) Add generic rhai script to transform tool
• Generate radial grid in x,y in grid tool
  • Make --output-format=lines output the rings as POLYGONs, so that smooth smooths just them, and not the radial spokes.
  • Maybe tunable enough that it should be its own radial tool?