make some field names in Aggregate more obvious, to distinguish the special case GROUP_CONCAT fields from the normal fields

The purpose of this is to simplify the code for the individual cases to make it easier to implement analytic (windowing) functions.

for the "duplicate key exception" test, make it a little more flexible, because the format of the VALUES clause varies a little depending on the type of the index.

Issue 482: class LobStorageBackend$LobInputStream does not override method int avalaible() from InputStream

Add sufficient ClientInfo support to our javax.sql.Connection implementation to make WebSphere happy.

move the DatabaseEventLister into inner classes - makes it easier to see what belongs to what, especially when some of the the overriden methods are very similar to methods in the superclass (TestBase)

change the PageStore#changeCount field from an int to a long, to cope with databases with very high transaction rates.

somebody reported an error, and they think the PageStore#changeCount field has wrapped and become negative.
Put a check in place to make such a situation more obvious.

Issue 481: Further extensions to PgServer to support better support PG JDBC, patch from Andrew Franklin.