- post-review changes

- post-review fix regarding Item_fields
- added test for the changed name resolution

- more tests, post-review changes, bug-fixes, simplifications, and improved comments

- Changed name resolution for GROUP BY so that derived columns do not shadow table columns
  from the FROM clause. As a result GROUP BY now is handled as a true ANSI extentsion.
- Issue a warning when HAVING is resolved into ambiguous columns, and prefer the columns from
  the GROUP BY clause over SELECT columns.

  Fixed the pre-caching of functions. It now gives the expected stack overrun
  error for functions recursing too deep.

  ...and no ALTER privilege either.
  For now, only the definer and root can drop or alter an SP.

Removed the support for renaming SPs. It's non-standard, conflicted with a standard
syntax, and was a bit broken anyway.

  Typos in comments.

into gw.mysql.r18.ru:/usr/home/ram/work/5.0

into sanja.is.com.ua:/home/bell/mysql/bk/work-view-5.0

into rurik.mysql.com:/home/igor/dev/mysql-5.0-0

  Post-merge fixes.
sql_select.cc:
  Post-merge cleanup.

check option build only according most top VIEW  CHECK OPTION TYPE  (BUG#5993)

  Remove compiler warning 'skip_auto_inc_decr' : unreferenced local variable in Visual C++; of course, I still have to check Monty's auto-inc patch in whole

into rurik.mysql.com:/home/igor/dev/mysql-5.0-0

  Fixed bug #6187: a wrong initial setting for const_item_cache
  in Item_cond::fix_fields.

into rurik.mysql.com:/home/igor/dev/mysql-5.0-0

  Post automerge correction.

  Added the code processing on expressions for applying
  multiple equalities.
sql_select.cc:
  Post-merge fixes for Item_equal patch.
  Added the code processing on expressions for applying
  multiple equalities.
Many files:
  Post-merge fixes for Item_equal patch.
item_cmpfunc.cc:
  Post-merge fixes for Item_equal patch.
  Fixed a problem when an equality field=const cannot be applied to
  the predicate P(field,c) for constant propagation as a conversion
  of field is needed.
item.h, item.cc:
  Fixed a problem when an equality field=const cannot be applied to
  the predicate P(field,c) for constant propagation as a conversion
  of field is needed.

test results corrected