No access to fitted normalizer from variogram estimation

[MuellerSeb]

If using fit_normalizer=True during variogram estimation, one can't access the fitted normalizer afterwards (in v1.3.0rc2):

bin_center, gamma = gs.vario_estimate((x, y), field, normalizer=gs.normalizer.BoxCox, fit_normalizer=True)

It should return the fitted normalizer as well, when fitting it:

bin_center, gamma, normalizer = gs.vario_estimate((x, y), field, normalizer=gs.normalizer.BoxCox, fit_normalizer=True)

In order to use it afterwards in SRF or Krige.