Add option to skip changed signal on an orient event

[tom-daff-cresset]

This change introduces an optional argument to the orient function that stops the changed signal from being dispatched.

This is necessary where the changed signal would trigger another orient in an infinite loop. For example, to synchronise instances over a network, messages can be sent between them by the changed message handler which would trigger an orient in the other instance. However, that orient must not trigger an identical reply, or it will create an infinite loop.