PostgreSQL, Make use of new type cast encoders and decoders provided by
latest ruby-pg gem for integer, float, bytea, boolean and array types.

It extends the statement pool, so that it stores several fixed parameters
in addition to the prepared statement key of the cached query.

This currently breaks compatiblity with the java port of ruby-pg, but it
will hopefully follow soon.
PostgreSQL, Add input and output type casts for values without column information.