ecpg does not understand enum datatypes.

The complete structure definition has to be listed inside the declare
section of the structure variable for ecpg to be able to understand it.

Variable type bool has to be checked. I never used it so far.

Missing statements:
 - exec sql type
 - exec sql define
 - exec sql prepare
 - exec sql allocate
 - exqc sql free
 - SQLSTATE
