cutThruAll fix for non-planar faces

[adam-urbanczyk]

This will resolve #355

[jmwright]

@adam-urbanczyk I think it looks good.

[codecov]

Codecov Report

Merging #604 (559e179) into master (8fcfb02) will decrease coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #604      +/-   ##
==========================================
- Coverage   94.27%   94.22%   -0.05%     
==========================================
  Files          29       29              
  Lines        6353     6351       -2     
  Branches      676      675       -1     
==========================================
- Hits         5989     5984       -5     
- Misses        226      228       +2     
- Partials      138      139       +1     

Impacted Files	Coverage Δ
cadquery/occ_impl/shapes.py	91.92% <ø> (ø)
cadquery/cq.py	89.28% <100.00%> (-0.38%)	⬇️
tests/test_cadquery.py	99.04% <100.00%> (+<0.01%)	⬆️

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[adam-urbanczyk]

Great, merging