#171 Clean cmdlinparser interface

[Gert Wollny]

The cmdlineparser options interface needs different functions for --help and --help-xml. An interface should be created that makes it possible to achieve the same with the Visitor pattern to enable additional outputs, e.g. nipype or qml interfaces.

[Gert Wollny]

For the latter (i.e. create interfaces) the python code to create the man pages and html documentation could also be adapted.