remembering how to write setup.py scripts
add ListReadable and ListEditable

originally in heron f535b75d4cd2 Mon Sep 09 12:18:15 2013 -0500
generalize ListReadable, ListEditable beyond just local files
 - ConfigRd treats configparser options as read authorizations
 - simplify ListReadable, ListEditable a bit
ConfigEd treats config parameters as write authorization
note quirk in ConfigRd.subRdFile
add ConfigEd.fromRd() and ConfigRd.get()
factor fromRd out of ConfigEd to share with ConfigRd
oops... ConfigEd needs to change base to base.ro() in ro()
support defaults in ConfigEd.fromRd()
 - fix number of args in subRdFiles
 - fix ListEditable.ro()
 - don't call .ro() in walk_rd
Call outChannel with self before attempting to call write()