should work in Prepared Statements. Post-review changeset.

Problem: There are some commands which are avaiable to be executed in SP
         but cannot be prepared. This patch fixes this and makes it possible
         prepare these statements.

Changes: The commands later are made available in PS. RESET has been forbidden
         in SF/Trigger.

Solution: All current server commands where checked and those missing (see later)
          we added. Tests for all of the commands with repeated executions were
          added - testing with SP, SF and PS.

SHOW BINLOG EVENTS
SHOW (MASTER | SLAVE) STATUS
SHOW (MASTER | BINARY) LOGS
SHOW (PROCEDURE | FUNCTION) CODE (parsable only in debug builds)
SHOW CREATE (PROCEDURE | FUNCTION | EVENT | TABLE | VIEW)
SHOW (AUTHORS | CONTRIBUTORS | WARNINGS | ERRORS)
CHANGE MASTER
RESET (MASTER | SLAVE | QUERY CACHE)
SLAVE (START | STOP)
CHECKSUM (TABLE | TABLES)
INSTALL PLUGIN
UNINSTALL PLUGIN
CACHE INDEX
LOAD INDEX INTO CACHE
GRANT
REVOKE
KILL
(CREATE | RENAME | DROP) DATABASE
(CREATE | RENAME | DROP) USER
FLUSH (TABLE | TABLES | TABLES WITH READ LOCK | HOSTS | PRIVILEGES |
       LOGS | STATUS | MASTER | SLAVE | DES_KEY_FILE | USER_RESOURCES)