remove simplify from warp

[elalish]

Fixes #673

This simplification was added after someone found duplicate verts when warping a cylinder into a cone, but based on further discussion, it seems that does more harm than good. This PR also removes Simplify from SetProperties and CalculateCurvature - in those cases there was almost no chance it could simplify anything anyway. Now Simplify is only called by the Boolean ops, AsOriginal, and mesh import.

For now I'm not adding Simplify to the public API, mostly because I would rather have a better one that can collapse larger triangles accurately, rather than just removing degenerates like mine does. For now if you need Simplify you can call AsOriginal, or if you need to maintain IDs, you can create a new Manifold from GetMeshGL.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (8c77a6a) 91.66% compared to head (8c8e804) 91.65%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #677      +/-   ##
==========================================
- Coverage   91.66%   91.65%   -0.01%     
==========================================
  Files          37       37              
  Lines        4737     4734       -3     
==========================================
- Hits         4342     4339       -3     
  Misses        395      395              

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