Find the rules named rune

General Form: (find-rules-of-rune rune wrld)

This function finds all the rules in `rune`
rune. It returns a list of rules in their internal form (generally as
described by the corresponding `rewrite` runes only name rewrite-rules).

At the moment this function returns `refinement` rune, because there is no object representing
`refinement` rules. (`refinement` rules cause changes
in the `equivalence` rune, then congruence rules with that rune will be
returned — because `equivalence` lemmas generate some
congruence rules — but the fact that a certain function is now known to
be an equivalence relation is not represented by any rule object and so no
such rule is returned. (The fact that the function is an equivalence relation
is encoded entirely in its presence as a `equal`.)