added routine for testing caropty based plotting
[mapping] implemented CARTOPY backend for nicer map plotting. This works now.
[pep8]
[mapping] swith to cartopy as default backend for projections if possible
[BUGFIX][preprocessor] minor fix in case that output filename is provided without a pathname (test failed). Makefile now includes call for testing
[Makefile] put testdirectories in variable
Merge branch 'master' of https://github.com/pygeo/pycmbs
Merge branch 'master' of https://github.com/pygeo/pycmbs