(pre-push cleanups removing debugging code)


sql/event.cc:
  - comment
  - fix 80 cols
  - fix a crash when dropping a running event (after it has finished
    its work because the memory got freed in remove_from_cache but the event
    was still running)
sql/event.h:
  - add new method
sql/event_executor.cc:
  - remove printf-s
  - fix 80cols
  - fix message