Signal calculation

• Skip the calculation of the induced current for a given drift line segment if the start or end point does not have a valid weighting potential (indicated by a negative value of the weighting potential).
• Add an option to DriftLineRKF to compute the induced signal using the weighting potential (as opposed to the weighting field).

enabled an automatic merge when the pipeline for 070adbaf succeeds

mentioned in commit 4298a983

merged