Composite cor l1 norm
This MR adds a derived class, based on CompositeCORFinder, which has a L1 metric for the merit function. It seems to work better than the first reimplementation in Nabu, and is more in line with Paul algorithm. To use it: use CompositeCORFinderMetricL1 in place of CompositeCORFinder ( alias CompositeCOREstimator ). Nothing ha to be changed otherwise