- handle better non-latin1 identifiers


sql/event.cc:
  - introduce a wrapper to compare easily and correctly
  LEX_STRINGs
  - remove few unneeded variables
  - remove need_second_pass by restructuring the code. this brings
    performance boost because the code bails out from the loop once
    it hits what it looks for
  - handle ALTER EVENT name RENAME TO name  (throw an error message).
sql/event_executor.cc:
  - comment about DBUG_FAULTY_THR
  - indent fix
sql/event_timed.cc:
  - fix a problem when event name is not latin1. a cyrillic event name
    was crashing the parser so the I emulate SET NAMES utf8. The data is
    already in utf8, being loaded from the disk.
sql/share/errmsg.txt:
  add new error message