add "/debug" repl meta-command. remove remnants of old repl.
round out d_expr and close up an ambiguity in struct vs function.
round out t_expr.
add covering state to parsed constants.
start tracking position through some of the expressions.
track position through all expressions. :)
track the location of locals.
better logging of errors in the repl, and save history.
lots of hacking around transforms. pack locals now!
trap ^C. use a real scope.
rename runtime scope to avoid trouble.
use big-integer instead, so it will run in a browser.
some fixes for the new packrattle.
beginnings of reference, local, code.