C++ code documentation is not using the standard

In most other packages containing C++ code, we have switched to the bob::extension:: documentation classes. These classes have the advantage that:

1. We get a unified documentation.
2. We make sure all parameters are documented, including the expected type
3. We assure that the parameter names in the documentation and what the function expects are identical.

Additionally, we normally use the BOB_TRY and BOB_CATCH_... macros in order to automatically catch any exception and provide a nice Python exception message, and make the code more readable.

This package does use neither of them.