Improve error message when we have a unique constraint violation, displays the offending key in the error message


git-svn-id: http://h2database.googlecode.com/svn/trunk@4850 e6896862-9d19-0410-bfb3-e9fa5d50e656
Issue 478: Support for "SHOW TRANSACTION ISOLATION LEVEL", patch from Andrew Franklin 


git-svn-id: http://h2database.googlecode.com/svn/trunk@4851 e6896862-9d19-0410-bfb3-e9fa5d50e656
Issue 475: PgServer: add support for CancelRequest, patch from Andrew Franklin


git-svn-id: http://h2database.googlecode.com/svn/trunk@4852 e6896862-9d19-0410-bfb3-e9fa5d50e656
Issue 473: PgServer missing -key option, patch from Andrew Franklin


git-svn-id: http://h2database.googlecode.com/svn/trunk@4853 e6896862-9d19-0410-bfb3-e9fa5d50e656