M300433/python interaface integration 1

Created a new branch an cherry picked all mergable commits from my PyCdo python interface branch. This compiles and runs all tests successfully. PyCdo is currently not able to be build with this and a followup merge request is required. This merge request is only to avoid further divergance. The big part that is missing is splitting cdo.cc further as was done in the original python interface branch.
The cmake files and build system have not been tested and the complete cmake build system should be functional with the following merge request.