Python recursivePthLoader in action

Remove pth loader (site.py) from module, instead propagate the recursivePthLoader (#222). This allows recursive pth loading, which is needed for modules that themselves depend on modules. It also avoids special treatment / a collision of theses site.py files.

pth files are not generated anymore for buildInputs (#210), but only for propagatedBuildInputs. the build process, usually easy_install, is responsible to generate a pth file with the runtime dependencies. Use propagatedBuildInputs if this fails, e.g. for matplotlib.

Further cleanup:
- prefix setuptools
- man page naming consistency (#68)
- further cleanup