writeOBJ can take an arbitrary number of dimensions for vertices, but readOBJ can't

[yig]

I can call writeOBJ on a vertex matrix which stores an arbitrary number of dimensions for each vertex, and it will write every dimension out to the OBJ file. However, readOBJ doesn't match this behavior and only supports vertices with three dimensions.

[penghao94]

I do not think libigl can draw more than 3 dimensions model

[alecjacobson]

libigl is more than a mesh viewer, so I'm not too concerned whether the viewer can handle them.

I don't see a reason why not to load these objs (except that they're obviously non-standard so we're encouraging files that may crash/fail to read in other apps). A PR for this would be merged.