Rewrote Rz_to_rhoPol and redirected stdout

Rz_to_rhoPol has been rewritten to conform with the pyddww style. In
addition the functions __blockstdout__ and __releasestdout__ have been
implemented to redirect the terminal output by libkk to /dev/null. After
__blockstdout__ has been called __releasestdout__ has to be called to
redirect the stdout to the terminal again. If this is not done python
will NOT print anything to the terminal anymore!