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. The recursivePthLoader itself is not included in the pth file generated for propagatedBuildInputs (#257).

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 that also results in recompilation of everything depending on python:
- prefix setuptools (`python-setuptools` instead of `setuptools`)
- man page naming consistency (#68)

Package fixes that make use of the pth loader:
- pygobject
- pygtk

Packages now also available for 2.6
- pycairo
- pygobject
- pygtk/pygtkGlade

Release file for hydra python-rework jobset: release-python.nix