Added "re-plot" button in Plot window.

Signed-off-by: Nicola Ferralis <feranick@hotmail.com>
API: self.livePlotting() is renamed self.plotting()

Signed-off-by: Nicola Ferralis <feranick@hotmail.com>
Updated changelog

Signed-off-by: Nicola Ferralis <feranick@hotmail.com>