make freeze script working again (use Extensions/mkext.py as a base?)

Put PostScript on archive site

Incorporate with contrib status:
- additions to glmodule by rg3h
- Jaap's posixfile module (with locking)
- pthreads interface

Later:
- put the offending object in IOError and posix.error
- make module marshal work with user-defined file-like objects
- built-in help
- hierarchical module names
- PC binary