Fix SyncedList __eq__ and modify constructor
Fix SyncedList __eq__ and modify constructor

Add an optional argument ``callable_class`` to allow for callable
classes to use their __call__ method in SyncedList for validation.

joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue