Metadata (will add README on same PR)

• Metadata is updated and written
• Score prelims are cleaned where possible
• Some file issues:
  SWV335 and some others are missing anywhere for the prelim fields to write: I was concerned adding this manually would cause data anomalies
  SWV329 and others had layout atrocities already
  Some anomalies throughout e.g. redundant clefs that nonetheless don't impact extracted data quality

Since at this point the metadata and extracted dataset files are fine, I don't think these are pressing items but are worth calling attention to as future issues