[CM] replacement for "environment"

[Bill Schottstaedt]

The name "environment" is annoying; I was thinking that
these things are disembodied lets, so s7 ought to use
"let" instead.  I've come up with:

environment?          let?, islet
global-environment    rootlet
initial-environment   unlet
with-environment      inlet
outer-environment     outlet, coverlet
augment-environment   sublet, novelette
augment-environment!  varlet
current-environment   valet
error-environment     owlet, triplet, roulette
procedure-environment lambouillet

but I'm stuck on 

environment->list (pronounced "environmentalist" of course)
open-environment