The serializer has partial specializations for all templates. It is a
good basis if the connector/database requires strings close to the
standard.
The interpreter is unspecialized (and uses a static assert to say so).
It is a good basis if the connector/database requires a different
interpretation, e.g. re-writing the expression tree.
The interpretable_t implements three methods for interpretation:
serializing with the sqlpp::serializer_context, serializing with the
database's serialization context and interpretation with the database's
interpretation context.
This will allow database connectors to specialize the interpretation of
the expression tree and interpret queries in vendor specific ways where
required.
