So it's clear it's not about MatchRule at all.

Sort of a comeback of an old idea. It's either this,
or adding a third parameter soon for lexicons.
I went with this as this makes it easier to add yet
another thing to toss around, if such need ever arises.

1) MatchOperator was essentially a wrapper for "match" section of "apply" operator
2) Other operators like Repeat actually used ConjConditions directly, without using MatchOperator
   - so ApplyOperator could too!
3) The confusion was about "match" referring both to part that is matching
   sentence against match conditions, and the results of this matching process.
   That led e.g. to "match_operator" rule in grammar, which was unlike
   "strset_operator" rule and the like. "match_operator" was about
   the "match" section in "apply" and now it is more straightforward.
   Next step should rename "match_fit" to be actual "match_operator",
   consistent with "XXX_operator" for other XXX types.

Changing submatching syntax from "->" to ":"  and M, MA to be shorthand for ($m:_M):1 and ($m:_M):2, respectively.
Also, "M" is optional if followed by ":", "M:1" is same as ":1"

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

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.

The prefix like "$m:" signifies type in WCCL, but in Variables code it comes from template argument; in this particular example, the <Match> type.