[API,INTERNAL] replace linear fit by B-spline in peak width estimation
[INTERNAL] B-spline wavelength adjusted
[API,INTERNAL] new implementation of PeakWidthEstimator
[API] removes PeakWidthEstimator_ from MultiplexClustering
[TEST] PeakWidthEstimator class test added
[API] free pointer in destructor
[API] virtual destructor used
[API] now passing const references
Merge pull request #1035 from lars20070/fix/FeatureFinderMultiplex

B-spline interpolation for peak width estimation in MultiplexClustering class