[developers] Paraphrase grammars and SEMI's

[Ann Copestake]

the `existing paraphrase' you're referring to is the MWE stuff?  I
think that isn't really a good guide - I don't think we had a SEM-I or
a clear notion of internal/external when that was originally done.

The fact that part of the grammar-internal hierarchy is useful is
surely outweighed by the observation that adding to it (as would be
necessary for paraphrase) could mess up the grammar.  

Investigating whether we could declare parts of the hierarchy as
shared between internal and external might be interesting.

Ann