Add documentation blocks for all classes and methods.

[fubhy]

As the title suggests. This is a bit of an annoying repetitive task but should be done for all our methods regardless so that the documentation generator can properly render the api docs with human readable information.

In addition to the standard parameter and short description of the methods I would really like to see usage examples (code examples) in the documentation blocks too. Especially for some of the more complicated methods. We could consider adding small excerpts that also explain the meaning of the methods a bit better if the name is not 100% clear.