[Parser.pattern] Improvements

[floriancargoet]

Two points that could be improved in Parser.pattern:

1. For choices, patterns are always processed but for lines, patterns are only processed if the line has a tag. I don't see why this should be a requirement.
2. RegExp patterns are only processed if one wraps a regexp in the RegExp function (without new)
   • Parser.pattern(/foo/, () => {}) will not be processed
   • Parser.pattern(new RegExp("foo"), () => {}) will not be processed
   • Parser.pattern(RegExp("foo"), () => {}) will be processed
   • Parser.pattern(RegExp(/foo/), () => {}) will be processed
   • I don't see a reason for this restriction. It's fixable by replacing pattern.matcher == RegExp(pattern.matcher) with `pattern.match instanceof RegExp, which will work for all 4 cases.