Updated documentation files to reflect MariaDB and not the Maria storage engine or MySQL

Added (rewritten) patch from Percona to get extended statistics in slow.log:
- Added handling of 'set' variables to set_var.cc. Changed sql_mode to use this
- Added extra logging to slow log of 'Thread_id, Schema, Query Cache hit, Rows sent and Rows examined'
- Added optional logging to slow log, through log_slow_verbosity, of query plan statistics
- Added new user variables log_slow_rate_limit, log_slow_verbosity, log_slow_filter
- Added log-slow-file as synonym for 'slow-log-file', as most slow-log variables starts with 'log-slow'
- Added log-slow-time as synonym for long-query-time
Some trivial MyISAM optimizations:
- In prepare for drop, flush key blocks
- Don't call mi_lock_database if my_disable_locking is used

KNOWN_BUGS.txt:
  Updated file to reflect MariaDB and not the Maria storage engine
README:
  Updated file to reflect MariaDB
mysql-test/r/log_slow.result:
  Test new options for slow query log
mysql-test/r/variables.result:
  Updated result (old version cut of things at 79 characters)
mysql-test/t/log_slow.test:
  Test new options for slow query log
sql/Makefile.am:
  Added log_slow.h
sql/event_data_objects.cc:
  Removed not needed test for enable_slow_log (is done when the flag is tested elsewhere)
sql/events.cc:
  Use the general make_set() function instead of 'symbolic_mode_representation'
sql/filesort.cc:
  Added status for used query plans
sql/log.cc:
  Reset counters if no query_length (from Percona's patch; Not sure if needed, but can do no harm)
  Added extra logging to slow log of 'Thread_id, Schema, Query Cache hit, Rows sent and Rows examined'
  Added optional logging to slow log, through log_slow_verbosity, of query plan statistics
  Fixed wrong test of error condition
sql/log_slow.h:
  Defines and variables for log_slow_verbosity and log_slow_filter
sql/mysql_priv.h:
  Include log_slow.h
sql/mysqld.cc:
  Added new user variables log_slow_rate_limit, log_slow_verbosity, log_slow_filter
  Added log-slow-file as synonym for 'slow-log-file', as most slow-log variables starts with 'log-slow'
  Added log-slow-time as synonym for long-query-time
  Added note that one should use log-slow-filter instead of log-slow-admin-statements
  Updated comment from 'slow_query_log_file'
sql/set_var.cc:
  Added long_slow_time as synonym for long_query_time
  Added new user variables log_slow_rate_limit, log_slow_verbosity, log_slow_filter
  dded handling of 'set' variables to set_var.cc. Changed sql_mode to use this
sql/set_var.h:
  - Added handling of 'set' variables. Changed sql_mode to use this
sql/slave.cc:
  Use global filter also for slaves
sql/sp_head.cc:
  Simplify saving of general_slow_log state
  Use the general make_set() function instead of 'symbolic_mode_representation'
sql/sql_cache.cc:
  Added status for used query plans
sql/sql_class.cc:
  Remember/restore query_plan_flags over complex statements
sql/sql_class.h:
  Added variables to handle extended slow log statistics
sql/sql_parse.cc:
  Added status for used query plans
  Added test for filtering slow_query_log
sql/sql_select.cc:
  Added status for used query plans
sql/sql_show.cc:
  Use the general make_set() function instead of 'symbolic_mode_representation'
sql/strfunc.cc:
  Report first error (not last) if something is wrong in a set
  Removed compiler warning
storage/myisam/mi_extra.c:
  In prepare for drop, flush key blocks (speed optimization)
storage/myisam/mi_locking.c:
  Don't call mi_lock_database if my_disable_locking is used (speed optimization)

README

@@ -1,35 +1,44 @@
-This is a release of MySQL, a dual-license SQL database server.
-MySQL is brought to you by the MySQL team at MySQL AB.
+This is a release of MariaDB, a branch of MySQL.
+
+MariaDB is a drop-in replacement of MySQL, with more features, less
+bugs and better performance.
+
+MariaDB is brought to you by many of the original developers of MySQL,
+that now work for Monty Program Ab, and by many people in the
+community.
+
+MySQL, which is the base of MariaDB, is brought to you by Sun.
 
 License information can be found in these files:
 - For GPL (free) distributions, see the COPYING file and
   the EXCEPTIONS-CLIENT file.
-- For commercial distributions, see the LICENSE.mysql file.
 
+A description of the MariaDB project can be found at:
+http://askmonty.org/wiki/index.php/MariaDB
 
-For further information about MySQL or additional documentation, see:
-- The latest information about MySQL: http://www.mysql.com
-- The current MySQL documentation: http://dev.mysql.com/doc
+The differences between MariaDB and MySQL can be found at:
+http://askmonty.org/wiki/index.php/MariaDB_versus_MySQL
+
+Documentation about MySQL can be found at:
+http://dev.mysql.com/doc
+
+For further information about MySQL documentation, see:
+- The current MySQL documentation: 
 
 Some manual sections of special interest:
 
-- If you are migrating from an older version of MySQL, please read the
-  "Upgrading from..." section first!
-- To see what MySQL can do, take a look at the features section.
-- For installation instructions, see the Installing and Upgrading chapter.
-- For the new features/bugfix history, see the Change History appendix.
-- For the currently known bugs/misfeatures (known errors) see the Problems
-  and Common Errors appendix.
 - For a list of developers and other contributors, see the Credits
   appendix.
 
 A local copy of the MySQL Reference Manual can be found in the Docs
 directory in GNU Info format.  You can also browse the manual online or
-download it in any of several formats at the URL given earlier in this
-file.
+download it in any of several formats from
+http://dev.mysql.com/doc
 
 ************************************************************
 
 IMPORTANT:
 
-Bug or error reports should be sent to http://bugs.mysql.com.
+Bug or error reports regarding MariaDB should be sent to
+https://bugs.launchpad.net/maria
+Bugs in the MySQL code can also be sent to http://bugs.mysql.com