ENH: Expose figure handle and disable blocking (#107)
ENH: Expose figure handle and disable blocking (#107)

Exposed the handle to the figures of the multi scan plots so they could be manipulated after they were created. 

Also added a flag to allow the plot not be shown immediately after it was generated

* add figure handle to waterfall
* show_plot flag to waterfall

neutronpy/neutronpy,pseudocubic/neutronpy,neutronpy/neutronpy,granrothge/neutronpy,pseudocubic/neutronpy,granrothge/neutronpy