support quantifiers in rule invocation

We now have a first approximation of a working ruleset implementation. Basic
functionality of a rule nested within a ruleset is there.

Some todos to think about:

  * The emitted loop for a ruleset parameter can result in integer overflow in
    the case when the type being covered has a maximum value of VALUE_MAX.
  * There is no support as yet for startstates or invariants nested within
    rulesets even though the grammar supports this.
  * I have not yet tested '0 TO 10 BY 2'-style quantifiers.
  * I have not yet tested multiply-nested rulesets.
  * I have not yet tested colliding identifiers in quantifiers.