mei'o MEIhO experimental cmavo

Elidable terminator for selma'o MEIhE (which turns any number of sumti into a selbri-unit)

Needed to close a MEIhE expression to resume adding sumti to the parent bridi.

In notes:

Accepts any number of sumti and turns them into a selbri-unit that means "x1 is among the referents of these sumti".