Add plugin interface, and example shoot plugin.
Merge branch 'master' into plugins
implement setup! and teardown!
Add ddg plugin
Add `use-plugins!'
Add a debug plugin
Merge branch 'master' into plugins & fix existing plugins
debug.scm -> admin.scm
Add simple stdout based authentication
Add `quit' and `join' admin commands
Add a help command
Add `admin-command?' object property and `define-admin' form
Add `eval' admin command
Add catch-all misc module with source and ping commands
procedure returned by `decorate-admin' should have the same docstring as argument
Add docstrings for all exported plugin functions
Mark admin commands as such in the output of help
Remove debugging pk
Add GPL copyright header notice

Added header to new files, and added "This file is part of " to
existing headers.
Actually fix copyright headers