• Bug fix: versions before 1.2.0 would allow and ignore a trailing path
  separator passed to DirectoryWatcher or FileWatcher constructors, restore
  that behavior.
• In paths passed to DirectoryWatcher or FileWatcher constructors, remove
  multiple adjacent separators and . and .., so they will not be returned in
  events.
• Bug fix: on Mac, stop issuing assert(false) when a modifyDirectory event
  is ignored, so the unused events are silently ignored instead of throwing in
  debug builds.