Draft: Update of Ditaumasstools for lfv
Applies various fixes to the lepton flavour violating version of the DiTauMassTool.
Increases the default N of sigmas with which to vary the MET to 5.
Allows to adjust the beam energy (default 6500 GeV).
Adds the option to retry the fit with the other lepton ordering in the fully leptonic case (default true).