v1.0.6: burst variance analysis in its own window.

Compare within-burst FRET variation with the shot-noise limit of Torella et al., Biophys. J. (2011), https://doi.org/10.1016/j.bpj.2011.01.066. The proximity ratio follows the FRETBursts example (Ingargiola et al., PLOS ONE (2016), https://doi.org/10.1371/journal.pone.0160716; https://github.com/OpenSMFS/FRETBursts_notebooks/blob/master/notebooks/Example%20-%20Burst%20Variance%20Analysis.ipynb).