Factor MatchOperator into ApplyOperator to prevent confusion.

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.