* Provide backwards compatibility extension to name resolution of
  coalesced columns. The patch allows such columns to be qualified
  with a table (and db) name, as it is in 4.1.
  Based on a patch from Monty.

* Adjusted tests accordingly to test both backwards compatible name
  resolution of qualified columns, and ANSI-style resolution of
  non-qualified columns.
  For this, each affected test has two versions - one with qualified
  columns, and one without.