Implement anonymous terminals in productions.

[pintarj]

Sometimes declaring terminals can be verbose. Consider this Generz code example (variable Expression is declared elsewhere):

terminal if
terminal brace_left /{/
terminal brace_right /}/

variable While {
    production if Expression brace_left Expression brace_right
}

It works, but is boilerplate. A less-verbose equivalent syntax can be obtained allowing regular-expressions to be used as production nodes. The upper example would be then transformed to:

variable While {
    production /if/ Expression /{/ Expression /}/
}

Implement this feature.