add faceareas & edgelengths
add tight packed vertices and normals
add TetMesh.h and its IO
Fix faces read bug
add face_indices_tightpacked;
remove omp in header
add facilities of TetMesh, need_facetareas() and need_tetravolume()
add TetMesh::need_adjacentelements()
dihedral angle computation of tetrahedron facets; flip surface facets
add TetMesh::write()
add read_off for COFF
modified README.md
rewrite io of TetMesh
Merge branch 'master' of bitbucket.org:bobye/trimesh2 into win32