Parquet metadata

[jaimergp]

Still needs to include the measurement type, external indices and, if needed, provenance information for each kinase / ligand.

[schallerdavid]

https://stackoverflow.com/questions/52122674/how-to-write-parquet-metadata-with-pyarrow

[schallerdavid]

But it may be easier to just write paired parquet and JSON/YAML files with metadata.