BF,ENH: Fixed some timer problems producing obscure errors

- Moved timer deletion into a proper StopFcn callback, which seems
  to have resolved some weird error messages about a third argument
  during polling (presumably having to do with trying to poll when
  the timer had been deleted.
- Fixed notification, which was getting called with object array.
  This caused extremely strange messages about 'nuts' not existing.
- Fixed bug in envp setter, although this is still non-functional.
- Added verbose attribute