There's still a problem: if I ever want to use any of the special
scenario variables like 'screen', 'console', etc., then I can't use
'local-scope' in my scenario.
Long-overdue reorganization to support general 'dilated' reagents up
front. This also allows me to move tests that are really about unrelated
layers out of layers dealing with parsing.
Not entirely happy with this. Maybe we'll find a better name. But at
least it's an improvement.
One part I *am* happy with is renaming string-replace to replace,
string-append to append, etc. Overdue, now that we have static dispatch.
