[oss6]

• Read raw data through Spectra instead of mzR, with identical results. mzRback is deprecated. Spectra, MsExperiment, BiocGenerics, S4Vectors and IRanges move to Imports and MsBackendMsp is suggested.
• purityA gains spectra, fragSpectra and avSpectra slots. purityA() accepts Spectra, MsExperiment, XcmsExperiment and mzStack datasets and reads each file once.
• frag4feature(), filterFragSpectra(), the averaging functions and the writers work from the Spectra slots, with each linked scan stored once.
• purityD gains avSpectra and experiment slots and accepts an MsExperiment. msfr CSV peak lists are read through Spectra.
• New accessors purityTable(), groupedSpectra(), allFragSpectra(), averagedSpectra() and averagedPeaks() return the legacy shapes or Spectra. options(msPurity.legacySlots = FALSE) leaves the legacy slots empty with identical outputs. updateObject() converts saved objects.
• mzStack peaks are read through MsBackendParquet, and convertLibraryToMzstack() accepts a Spectra object.
• allFragSpectra() names the scan of every peak correctly. The legacy all_frag_scans table and the frozen SQLite output keep the old pid numbering.
• Fix averaging after filterFragSpectra(rmp = TRUE) when every spectrum of a feature loses all its peaks.
• Fix createMSP(method = "max") with one passing peak, and its choice of scan when a scan is linked to a feature more than once.
• Add parity references and tests, a purityA memory benchmark and a NEWS entry. Bump the version to 1.37.5.