Added ORDER BY optimization

This fixes the query cache problem on windows.

Fix for new bug in CREATE TABLE when sorting keys.

  mirror updates

Cleanup of multi-table-delete in sql_yacc.yy
Changed syntax of MAXIMUM QUERIES PER HOUR to MAX_QUERIES_PER_HOUR to
not get too many reserved words.

Fixes for building MySQL with gcc 3.0
Added SIGNED / UNSIGNED casts
Fixed core dump bug in net_clear() with libmysqld.
Back to using semaphores in query cache.
Added 'Null' and 'Index_type' to SHOW INDEX.

  Remove erroneous warning of a duplicate key when the key in a UNIQUE secondary index contains a NULL

into donna.mysql.fi:/home/heikki/mysqlm

into sinisa.nasamreza.org:/mnt/hdc/Sinisa/mysql-4.0

creates proper column types, out of any function, expression or from
other tables.

  More clarification of startup parameters

  Fix a syntax error which slipped into previous changeset

  Clarification of InnoDB startup options

  Add unintentionally removed text

  Make InnoDB startup option samples easier to understand, do not recommend too big log files

  Make InnoDB startup option samples easier to understand, recommend not setting log files too big, because recovery slow

  Eliminate a gcc compiler bug in inlining

  Make os_file_flush to ignore the error we get from a raw device in fsync

Now everything compiles and all tests are passed .... ;o)

What a push !

One more notice:

limiting number of queries per hour for different users has been done
on 4.0.1 , but I can port it to 3.23.* 

This will require only certain changes, like number of columns in user
table.

I will also make a test case for it, after it is approved by Monty, 
as result file will depend on the error message text.

* multi-table updates
* new paid feature for limiting number of queries per hour for users
* optional syntax for multi-table deletes
* optimization for SQL_CALC_FOUND_ROWS
* a small addition for CREATE .. SELECT that will be of future use

I know that all this will require many additions to documentation, 
which I have not done, but I am at Arjen's disposal to help him document
all this.