Commenting and refactoring work

Signed-off-by: Tobias Lorenz <tobias.lorenz@etas.com>
Improved Doxygen source code generation.

* Instead of several Doxyfiles, there is now only one.
* There is no have @file attribute in every file. Simplicity.

Signed-off-by: Tobias Lorenz <tobias.lorenz@etas.com>
Merge branch 'master' of https://github.com/etas-lorenz/busmaster.git