Change messages like this:

ERROR:  ExecInsert: rejected due to CHECK constraint insert_con

To be like this:

ERROR:  ExecInsert: rejected due to CHECK constraint "insert_con" on
"insert_tbl"

Updated regression tests to match.

I got sick of seeing 'rejected due to CHECK constraint "$1" in my log and
not being able to find the bug in our website code...

Christopher Kings-Lynne