Extend PCA to support classifying mass spectra (nominal)

[eselmeister]

Peaks, scans and other input types are supported already. Additionally support mass spectral data.

[eselmeister]

[eselmeister]

169: Acer saccharum https://en.wikipedia.org/wiki/Acer_saccharum

418: Betula alleghaniensis https://en.wikipedia.org/wiki/Betula_alleghaniensis