* Added improved .msh reader/writer + tests + example,
with fixes proposed by @qnzhou
put append_mat_to_vec into igl::internal
* Update tutorial number.
* Changed tutorial code to use example from https://github.com/libigl/libigl-tutorial-data/pull/1 and flat shading
* Remove commented code.
* Rename tutorial number + update tutorial data.
Co-authored-by: Jérémie Dumas <jdumas@users.noreply.github.com>
Co-authored-by: Jérémie Dumas <jeremie.dumas@ens-lyon.org>
