made SplineSpectrum::Navigator public (not usable otherwise); fix compile error (VS2013) due to missing include; fixed interface(names); fixed intendation
fixed segfault (>=0 issue)
hide default Ctor; add missing tests (no content)
fixed loop vars
error handling for faulty spectra; more cleanup and tests
Merge pull request #835 from cbielow/fix_splineSpectrum

Fix spline spectrum