PyTerrier 1 roadmap

Must Have:

• dependency and usage that doesnt require Java - see https://github.com/terrier-org/pyterrier/tree/java_optional - see #553
• pt.get_dataset() not doing terrier tokenisation by default ⌨️
• #508 needed first
• Fix Terrier's tokenisation of queries with punctuation etc. ⌨️
• remove pt.cache - #562 ✔️

Should Have:

• Merging of pyterrier-alpha features:
• pta.io ✔️
• pta.validate ✔️ #561

Could Have:

• remove pt.BatchRetrieve
• remove pt.DFIndexer

(See also https://github.com/terrier-org/pyterrier/wiki/Planned-Removals-and-Deprecations)