Ensure grouping of alternation is needed before applying

[jsim2010]

Currently grouping occurs when the alternation is applied. This results in regexes with just the alternation, ex: "aa" | "bb", being grouped, i.e. (?:aa|bb), even though the grouping is not needed, aa|bb. Ideally, this grouping only applies if it is necessary, ex: ("aa" | "bb") + "c" = (?:aa|bb)c.

[jsim2010]

Need to check that an alternation has not already been handled. For example:

("aa" | "bb") + Ch::whitespace() + "cc" = (?:aa|bb)\scc instead of (?:(?:aa|bb)\s)cc.