Fix PolarLine.atAngles: use temp point

We are using a temp point because we update the start, and then
calculate, but that shouldn't be a problem (and isn't except a case
@[761,26])
Add test cases to tests
Fix PolarLine: clear the coefs cache on __make__
Typos
No need to delete the coefsCache
Actually fix PolarLine: dumb forgotten line
Batches: cache batches
Move NewSections.js
Huge fixes to batches

Hopefully it works perfectly, but it probably needs simplifying
Add isOneWholeBatch check in tests
Batches: remove batch typo