Peak selector GUI for Jupyter

If the automatic peak finding algorithm identifies the wrong peaks in the spectra or if the user is not satisfied with the selection of those peaks, it can use PeakSelectorWidget class with a previously binned xarray and selected the peaks manually clicking on them:

The widget is meant to be used twice:

• During the first time, a set of peaks should be selected. Once done, the user should click on Repeat selection
• This second time is used to grab the same peaks that will be used later on to compute the uncertainties in the peak selection, in order to avoid possible human errors