mCBM 2020: in time win evt builder, reject seeds if part of reference det...

mCBM 2020: in time win evt builder, reject seeds if part of reference det cluster from previous seed

=> This should fix the problem that in AllowOverlap mode events where cloned/split due to the cluster size when using TOF as reference
=> a mean cluster size of <N> in the reference detector was leading to N events for each real seed in this mode!