Implement in-place mutation operators for MutableSet, MutableList

Implement in-place mutation operators for MutableSet, MutableList

Implemented in-place mutation operators ``__ior__``, ``__iand__``,
``__ixor__`` and ``__isub__`` for :class:`.mutable.MutableSet`
and ``__iadd__`` for :class:`.mutable.MutableList` so that change
events are fired off when these mutator methods are used to alter the
collection.

Change-Id: Ib357a96d3b06c5deb6b53eb304a8b9f1dc9e9ede
Fixes: #3853