v4.1

• Protection agains buffer overflow and negative indexes in
  __getitem__ and __setitem__ for objc.varlist instances.

• Fix incorrect metadata for +[NSEvent addLocalMonitorForEventsMatchingMask:handler:]

• Fix incorrect and misleading error message in the exception
  that is raised when return a value from a block that should not
  return a value.

• Issue #223: Fix hard crash when executing help(Cocoa)

  Fetching the help for PyObjC framework wrappers isn't very useful due
  to the sheer size of the output (4.5 million lines of output for
  help(Cocoa) at the moment), but shouldn't cause a hard crash of
  the interpreter.

  Reported by Dave Fuller

• Issue #218: Explictly cause an ImportError when reloading objc._objc

  Reloading the PyObjC core extension now raises an ImportError because
  this cannot work and used to raise a rather vague error.

• Updated metadata for Xcode 9.2

• Added missing MAC_OS_X_VERSION_* constants

• Fix memory error in struct wrappers which resulted in
  a use-after-free error in the initializer for structs.

• #135: Add bindings for frameworks :doc:Security </apinotes/Security>,
  :doc:SecurityFoundation </apinotes/SecurityFoundation> and
  and :doc:SecurityInterface </apinotes/SecurityInterface>.

  The bindings for the Security framework don't expose a
  number of older APIs that were deprecated in macOS 10.7.

• #129: Add bindings to libdispatch.

  These bindings require macOS 10.8 or later, libdispatch was
  available earlier but macOS 10.8 changed the API in such a
  way that wrapping became a lot easier.