Improved lazy plotting in HyperSpy

[magnunor]

With the improved handling of navigator signal generation of lazy signals in HyperSpy via https://github.com/hyperspy/hyperspy/pull/2631, the functionality added in https://github.com/pyxem/pyxem/pull/655 should be removed.

We should also check that all the functionality is replicated.

I guess it can be handled in a small release, after the next HyperSpy release.

[magnunor]

Reminder to self to remove this functionality: https://github.com/pyxem/pyxem/blob/master/pyxem/signals/diffraction2d.py#L1308, since it is superseded by a released HyperSpy functionality.