Add angular precision

[winksaville]

This gives flexibility to the programmer when exporting.

[codecov]

Codecov Report

Merging #424 into master will not change coverage.
The diff coverage is 95.00%.

@@           Coverage Diff           @@
##           master     #424   +/-   ##
=======================================
  Coverage   93.59%   93.59%           
=======================================
  Files          25       25           
  Lines        5306     5306           
  Branches      552      552           
=======================================
  Hits         4966     4966           
  Misses        215      215           
  Partials      125      125           

Impacted Files	Coverage Δ
cadquery/occ_impl/exporters/__init__.py	92.63% <90.00%> (ø)
cadquery/occ_impl/shapes.py	90.74% <100.00%> (ø)
tests/test_exporters.py	100.00% <100.00%> (ø)

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[winksaville]

LGTM

[adam-urbanczyk]

Looks good, thanks @winksaville . @jmwright do you want to merge?

[jmwright]

Thanks for the contribution @winksaville