Features Not Yet Implemented

[mobiusklein]

This issue is a running list of features that are not yet implemented in the Python implementation or in the repository in general:

• [x] Clusters - This feature was added on late in the game and is only being specified now. We should also hand-craft some examples to be able to do something with.
• [x] Attribute set in groups - This feature should be straight-forward to implement.
• [x] sptxt backend attribute parsing - This requires some familiarity with the sptxt format. The syntax is identical to msp, but uses different names for some things. Documentation is missing from http://tools.proteomecenter.org/wiki/index.php?title=Software:SpectraST
• [x] Tabular file parsing - Something to read CSV or TSV files from search tools like Spectronaut or DIA-NN.
• [x] Library-level JSON Schema - The drafted PR needs to be re-worked to cover the year's worth of changes since it was first written.
• [ ] GNPS MGF, MassBank TXT, other MGF?

There are always more read-only backends to implement or improve:

• The BiblioSpec backend could get considerably better with a more complete and up to date example file.
• A generic mzIdentML + mzML/MGF read-only backend would let us convert ID experiments directly, but this is "hard" to do well.
• More attribute handlers for parsing msp comments from the wild will help cover more use-cases.