Update bibliography tags for consistency

[masinter]

Additionally, the tags themselves need to be cleaned up to be only the ones relevant to users, consistent UPPER/lower case spelling, singular/plural, synonyms/very-similar, etc.
This file: tagsGroup2.json has all items with any tags (only the tag, key, and title fields). These are grouped by the tag as lower case, then within each group's "tags" array, the items are grouped by tag as in Zotero. (Some have 3 capitalization variants.)

Originally posted by @MattHeffron in #2348