First cut on mapping exceptions to mysql error messages/error codes/sql states:
+ Introduce an error mapper, which takes an ErrorInfo block and converts it into either a
  MyErrorResponse (for the wire) or a SQLException (for a server db connection).
+ Add a universe of dve specific errors.  These are mildly typed insofar as you can
  declare them to be of type tuples (i.e. <String,String>) which allows for compile
  time checking.
+ Add a universe of mysql specific errors.  These are also mildly typed, and by default
  are tied to a single dve error, although there is the ability to use a single mysql
  specific error to handle multiple dve specific errors.
+ Stop wrapping everything in a PEException prior to exiting the execution engine.  In
  particular, for SchemaExceptions, propogate the naked exception so we can get at the
  ErrorInfo.
+ Assert on mysql error formatters, SchemaExceptions, etc. in the tests.
Arrange for filtering to continue to work for the replication slave.  Use the ErrorInfo on
the SchemaException to pick out the pertinent errors and construct the appropriate name for lookup.