TESTS TO ADD

* CACHE-TABLE-QUERIES
* Test that ":db-kind :key" adds an index for that key. This is complicated by 
  different backends showing autogenerated primary key in different ways.
* :db-constraint tests
* test *db-auto-sync* 
* for-each-row macro
* owner phrases for postgresql and oracle backends
* Number and Char field types
* Add test case for return type of (setf slot-value-using-class)
* symbol slot
* generalized-boolean slot

OPTIMIZATIONS
 
* Revisit result-type list creation, perhaps caching
* Rework LIST-ATTRIBUTE-TYPES and LIST-INDEXES such that they exhibit their 
  current behaviours using single database queries.  

POSSIBLE EXTENSIONS

* improve large object api and extend to databases beyond postgresql 
* add support for prepared statements