Documentation is very poor and no users guide is available

Created by: siebenkopf

I had a look into the bob.math documentation and found that there are some classes and functions, which have little to no documentation. Also, many of the parameters lack documentation (which can be seen in the automatically generated TODO list in the documentation: https://www.idiap.ch/software/bob/docs/latest/bioidiap/bob.math/master/index.html (which I have moved below the documentation in the rebind branch that I will merge soon).

It would be nice if anyone (who knows, what the parameters are) could spend some time to document them. A proper users guide would be nice as well.