New Features for DESY Testbeam Analysis

This MR contains a couple of new features which are required for the DESY testbeam analysis, namely

In [Tracking4D]:

• require a certain detector to be part of the track (even if number of required clusters on track is smaller than the total number of detectors (minus DUT)). This is needed to make sure the Timepix3 provides a hit for each track such that its timestamp can be used.
• Use a defined detector to set the timestamp of the track (or: use the average of all cluster timestamps on the track as it was implemented previously). This is needed as the Timepix3 shall define the track timestamp and not the average of 1x Timepix3 + 6x Mimosa26 which only have the "not-so-precise" trigger timestamp.

In [ClusteringSpatial] and [Clustering4D]:

• new 1D histogram of cluster timestamps

In [ClusteringSpatial]:

• if available attach trigger timestamp to cluster (before, the timestamp of clusters from this module was always 0). This way, [Tracking4D] was not usable with Timepix3 + Mimosa26

More things to be added...no need to review yet.