Arc & circle generation that does not calculate sin & cos for every vertex

[ftvkyo]

• When offsetting a point, the performance improvement seems to be ~45%
• When offsetting line strings and polygons, the performance seems to be similar (current implementation shows an improvement of ~5%, but minor changes easily make performance worse by ~2% instead), so it's probably other factors that affect it the most
• This may help address this issue: Strange dilating behaviour  #27
• Draft PR for now because I need to review & likely update the tests

Open to feedback :)

• Review & update the tests
• Add a benchmark that checks fn create_arc in (almost?) isolation

[ftvkyo]

Output of the updated test_point_offset:

[lelongg]

I'm open to merge once you are ready

[ftvkyo]

I don't think I'd manage to get around to that create_arc benchmark I mentioned anytime soon, so if you are happy with it, please do merge, thank you!