Return a deep copy of a Rule.
A deep copy implies
that for a rule that contains other rules (i.e.
RuleAlternatives,
RuleCount,
RuleParse,
RuleSequence,
RuleTag)
the sub-rules are also copied.
Note: copy differs from the typical use of clone
because a clone is not normally a deep copy.
Return:
deep copy of a Rule.
Return a string representing the Rule
in partial
Java Speech Grammar Format. The string represents a portion of
Java Speech Grammar Format that could appear on the right hand
side of a rule definition.
Return:
a printable Java Speech Grammar Format string.