MuGirlStau - Pick up LRT tracks in the chain

Moin everybody,

I've been asked whether it's possible to include the LRT tracks also into the Stau reconstruction chain. This MR proposes a solution minimally invasive to the configuration. The physics performance gain for susy signal samples has not been checked. If someone wants to pick the task up before the feature freeze mid february, feel free to do so.

Tagging: @labruce, @masahiro, @gabarone, @nicolaid, @jgonski, @thomsone, @sagara17, @goblirsc, @shlomit, @ztarem, @ekajomov