Plot smoothed data

[dmccloskey]

hull_points = subordinate.getConvexHull().getHullPoints() is empty.

[dmccloskey]

fix the following tests in OpenMS:

• [x] Test #1575: TOPP_OpenSwathAnalyzer_test_7_backgroundSubtraction_out1
• [x] Test #1574: TOPP_OpenSwathAnalyzer_test_7_backgroundSubtraction