Merge 'column_attr' into 'trunk'

Merge 'column_attr' into 'trunk'

r10954@hex:  nigel | 2009-02-24 12:28:54 +0000
Merged in column_attr branch:-
  Resultset attributes now include the following items to specify
  "select" and "as" values:-
     columns    - list of columns (specifies both select and as)
     +columns   - list of extra columns (specifies both select and as)
     select     - list of select values only
     +select    - list of extra select values only
     as         - list of as values only
     +as        - list of extra as values only
     include_columns - deprecated alias for +columns
  The values for columns/+columns/include_columns may include hashrefs,
  in which case the hash is interpreted as {as => select}, allowing
  queries involving functions to be specified without needing the
  information to be split into 2 separate places.