[matrix] Message-free Matrix

[Emily M. Bender]

Dear Matrix community,

As a follow up on my previous posting about the message-free matrix,
I wanted to alert you to a side effect of the change we made which
might affect your grammars.  Since clause-selecting lexical heads need
to drop in a qeq (handle constraint) for the embedded clause, the
type norm-sem-lex-item no longer inherits from no-hcons-lex-item.
In some cases (e.g., regular old nouns) you still want to inherit
from no-hcons-lex-item, or else the unconstrained HCONS value will
break the diff-list appends that send the non-empty HCONS values up
the tree.

Emily