Migrate to Meshes.jl

[AleMorales]

At the moment we have our own implementation of 3D mesh. Meshes.jl would handle attributes more elegantly. We may also be able to rely on future packages built on top of Meshes.jl (and maybe even get some performance advantages?)

[AleMorales]

We now handle attributes per triangle in a better way. It is not clear what we win with Meshes, we already have very optimized primitive constructors. It is not clear what we gain by this transition.