Add a tolerance threshold optional flag to gmclash - ignore clashes below the threshold

Add a tolerance threshold optional flag to gmclash (-t). The default value is zero. If the flag is used a distance in millimeters must be indicated. Then gmclash ignores clashes below that threshold value.

FYI @dellacqu

added FullSimLight label

requested review from @dellacqu and @boudreau

approved this merge request

enabled an automatic merge when the pipeline for fbb1d1c9 succeeds

merged

mentioned in commit c9bcc6d1