Show-rules
Sets whether or not RP-Rewriter should print used rules when rewriting
a conjecture.
(show-rules <nil-OR-t-OR-:cnt>) submits an event that changes
RP-Rewriter's behaviour on saving and printing used rules. When set to t, it
prints rule in a fashion similar to the built-in rewriter but only differently
for meta-rules. When set to :cnt, it also attaches a number to each rune
showing how many times they are used, and how many times they failed due to
unrelieved hypotheses. These entries are saved in rules-used field of stobj
rp::rp-state.
