Also, adding M in grammar to be shorthand for $m:_M (vargetter) op in match context.

fix crashes in markmatch / unmarkmatch caused by taking a reference to a shared pointer instead of just making a copy, and a typo

Basically a ParsedExpression wrapper for Variables and ApplyOperator.

MatchVector, AnnotationMatch, TokenMatch are now MatchData
MatchData is value_type of Match which now has get_value/set_value
Match has also copy construction working properly now
Default value for Match holds MatchVector so adding $m:_M var in grammar works as intended.