Attempt to clean up ExecSql() in JDBC

Hi,

Attached is my attempt to clean up the horrors of the ExecSQL() method in
the JDBC driver.

I've done this by extracting it into a new method object called
QueryExecutor (should go into org/postgresql/core/) and then taking it
apart into different methods in that class.

A short summary:

* Extracted ExecSQL() from Connection into a method object called
QueryExecutor.

* Moved ReceiveFields() from Connection to QueryExecutor.

* Extracted parts of the original ExecSQL() method body into smaller
methods on QueryExecutor.

* Bug fix: The instance variable "pid" in Connection was used in two
places with different meaning. Both were probably in dead code, but it's
fixed anyway.

/Anders

PS.: If anyone has any idea what the variable names "fqp" and "hfr" stand
for, please tell me! :)

_____________________________________________________________________
A n d e r s B e n g t s s o n ndrsbngtssn(at)yahoo(dot)se
Stockholm, Sweden