Fix the zebra polygon

[elalish]

Fixes #831, or at least it had better before we merge this. I removed a few holes and got it to triangulate properly, which gives us a few clues. The polygon appears to be valid. I haven't managed to make a minimized version yet though.

[elalish]

Nice work @kintel - this one horribly excellent polygon test revealed 4 different triangulator bugs. I still need to make the upside-down version work, but I'll save that for tomorrow. For now I want to bask in making this ridiculous zebra finally work.

[elalish]

@pca006132 It seems our Windows CI got updated or something - suddenly it's very picky about possible data loss: C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\VC\Tools\MSVC\14.29.30133\include\xutility(5532,1): warning C4267: 'argument': conversion from 'size_t' to 'int', possible loss of data [D:\a\manifold\manifold\build\src\manifold\manifold.vcxproj]
Do you know an easy way to get it to shut up?

[pca006132]

No idea, but should be easy to fix. Will do with #802.

[pca006132]

but the actual error seems to be

fatal error C1128: number of sections exceeded object file format limit: compile with /bigobj

https://stackoverflow.com/questions/69903253/cmake-bigobj-no-such-file-or-directory

this may work:

if (MSVC)
  add_compile_options(/bigobj)
endif ()

[pca006132]

btw I feel like the zebra.cpp file should be placed within another folder in the test directory, as I can foresee us adding more and more complicated test cases in the future.

[elalish]

Perfect, that's exactly what I needed! Agreed about the separate test folder, but let's wait until we have another file in that category to create it.