DO NOT MERGE TO 4.1: charset changes can cause problems in a downgrade 4.1.1 -> 4.0.18

  DO NOT MERGE TO 4.1: add code for automatic downgrade 4.1.1 -> 4.0 if the user has not created multiple tablespaces yet

Added support for lower_case_table_names=2, which is to be used on case insensitive file systems.
This tells MySQL to preserve the used case of filenames and database names to make it esier to move files between cases sensitive can case insensitive file systems (like Windows and Linux)

into bar.intranet.mysql.r18.ru:/usr/home/bar/mysql-4.0

  Like did not work in some cases
  ,

  Do not assert in log0log.c, line 856 if ib_logfiles are too small for innodb_thread_concurrency. Instead, print instructions how to adjust my.cnf and call exit(1).

   (BUG#2156)

into serg.mylan:/usr/home/serg/Abk/mysql-4.0

Bug #2163

into eagle.mysql.r18.ru:/home/vva/work/BUG_2086/mysql-4.0

into eagle.mysql.r18.ru:/home/vva/work/BUG_2086/mysql-4.0

Fixed not updated test from last changeset

into mysql.com:/my/mysql-4.0

into mysql.com:/home/mysql_src/mysql-4.0

release the mutex before exiting the function, or it will be kept forever
(=> START SLAVE, STOP SLAVE, etc will hang).

(bug #2086)

into eagle.mysql.r18.ru:/home/vva/work/BUG_2023/mysql-4.0

(char * -> const char*)

into mysql.com:/home/mysql_src/mysql-4.0

more general message when slave can't start because of incorrect
replication information, the previous one was sometimes a misleading
indication (i.e. sometimes the problem had nothing to do with
system permissions).
The perfect fix would be to report the exact error to the client
(instead of pointing the client to the error log); this is a bit
of work so it's more a development task:
WL#1088 "Move all hardcoded messages of replication to share/errmsg.txt".
I was not able to modify the errmsg.txt in these sql/ subdirectories:

danish
dutch
german
italian
portuguese
russian
spanish
swedish
ukrainian

   tagged/released
 - tagged ChangeSet@1.1655.1.3 as mysql-4.0.17

   a missing space)
 - Define the subject of the failure mail reports within the calling script
   instead of logger.pm

into sinisa.nasamreza.org:/mnt/work/mysql-4.0

in decimal type with prepended zero's.

into mysql.com:/my/mysql-4.0

Make ENGINE= an alias for TYPE= (Compabiltiy with 4.1)
Fix when using symlinked data files and realpath() is not working

into mysql.com:/home/mysql_src/mysql-4.0

"EE_ error codes (EE_DELETE, EE_WRITE) end up in the binlog, making slave stop".
The problem was that during execution of the command on the master, an error
can occur (for example, not space left on device, then mysqld waits and when
there is space it completes successfully: so finally it worked but the error
EE_WRITE remains in thd->net.last_errno and thd->net.last_error).
To know if finally the command succeeded, we test the 'error' variable in
every place, and if it shows no failure we reset thd->net.last_err* using
the function THD::clear_error() which is backported from 4.1.
A new test to see if now only real errors get to the binlog (note: the test
uses "rm").

Also a bit of memory free/alloc saving in log_event.cc (do not free the whole
mem_root after every query in the slave SQL thread: we can keep the initial
block of it; which will be freed when the thread terminates).