Added classes Statement, Statement_map
Merge commit

into mysql.com:/home/pem/work/mysql-5.0

into mysql.com:/home/kostja/mysql/mysql-5.0-root

- unused variable THD::con_root removed
- we don't need to bzero(&warn_root) just before init_alloc_root(&warn_root)
- we don't need to bzero(&transaction.mem_root) because we 
  bzero(&transaction) later in THD::THD
- we don't need to free thd->mem_root thd->transaction.mem_root
  in handle_one_connection because they are freed in THD::~THD
  which is called in end_thread later 

into mysql.com:/home/psergey/10-get-mysql5

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

into mysql.com:/home/pem/work/mysql-5.0

into mysql.com:/home/kostja/mysql/mysql-5.0-root

  Logging to logging@openlogging.org accepted
sql_union.cc, sql_select.cc, opt_range.h, opt_range.cc, opt_ft.h:
  Post-merge fixes
Many files:
  new file

for some items, which made aggregates like MIN(), MAX() and SUM() fail.

- dropped routines should not show up in status
- error handling for non-existing routines

+ some cleanup.

into bar.mysql.r18.ru:/usr/home/bar/mysql-4.1

  There were errors in cp850: in unicode, ctype and sort arrays

Fixed various bugs: setting local variables to NULL, SELECT INTO var now actually
might work, SELECT INTO with not row now gives a "no data" warning (instead of
the "empty query" error), etc.
Updated test cases accordingly.

into mysql.com:/space/my/mysql-4.1

into sanja.is.com.ua:/home/bell/mysql/bk/mysql-4.1

into mysql.com:/space/my/mysql-4.1

into mysql.com:/bk/mysql-4.1

into sanja.is.com.ua:/home/bell/mysql/bk/work-used_tables-4.1

into mysql.com:/space/my/mysql-4.1

into sanja.is.com.ua:/home/bell/mysql/bk/work-used_tables-4.1

into sanja.is.com.ua:/home/bell/mysql/bk/work-delete-4.1

into sanja.is.com.ua:/home/bell/mysql/bk/work-delete-4.1