Fix a #'setenv bug, merge other changes from GNU's env.el. 2007-12-14 Aidan Kehoe <kehoea@parhasard.net> * process.el (substitute-env-vars): Merge an example from GNU's docstring. * process.el (setenv): Pass nil as the default abbrev table to the #'read-from-minibuffer call, instead of passing the current value of the variable. Bug introduced by an incorrect sync from GNU by Ben; reported by Thomas Mittelstaedt in 47626712.40609@cadenas.de. Document the #'set-time-zone-rule call when TZ is set. Push the old value on to the beginning of setenv-history. (Both merged from GNU.) Document that we don't do the coding-system frobbing at this level that GNU does. Provide a commented-out, sample implementation of GNU's #'environment; document why I think we shouldn't include it.