Documentation

I've chosen Doxygen here as its very easy to work with, and allows natural documenting (ala javadoc)
A fair amount of Buxton (public) has now been documented, as can be seen by running doxygen on Doxyfile.
We could follow up in the future with a make rule to generate this.
Also note that currently static members are not documented as per the configuration. If it is desired, I can alter this.