Remove devel/py-ctypes (only needed by and supporting python24).
Remove PYTHON_VERSIONS_ACCEPTED and PYTHON_VERSIONS_INCOMPATIBLE
lines that just mirror defaults now.
Miscellaneous cleanup while editing all these files.
On request by joerg, prefix PKGNAME with py??- since it installs a python
library; this way all binary packages can coexist.
The separate packages will still conflict due to bin/datapkg though.