remove duplicate code
Mark conversion constructors of EigenMesh3D `explicit`
Working on mesh simplification for hollowed interior
Fix bug SPE-1074: crash with empty supports and disabled pad.
fix regression after refactor
Remove unfinished code
Fix missing includes and dumb comments
SPE-1072
Working but flipped normals with the interior.
Testing on treefrog passed
Oversampling for hollowed mesh should not be less than 3x
Flip back normals after simplify and remove redundant test code.
