[INTERNAL] fix for evaluation at last node
[TEST] now non-zero intensity at right boundary of test interval
[TEST] tests with sine added
[TEST] relative tolerance added
[TEST] smaller x interval for only 10 nodes
[TEST] test for boundary conditions added
Merge remote-tracking branch 'upstream/develop' into fix/CubicSpline
Merge pull request #931 from lars20070/fix/CubicSpline

[FIX] fixes evaluation of CubicSplines2d at last node
Merge remote-tracking branch 'upstream/develop' into feature/FeatureFinderMultiplex