New JDB fields

[danielchivvis]

titlehistory:

• predecessor_issn
• successor_issn
• predecessor_coden
• successor_coden

master (or other/new table):

• has_supplement
• is_supplement_to
• has_letters
• is_letters_to
• has_translation
• is_translation_to
• subject_areas
• notes_public

publisher:

• predecessor_publisher
• successor_publisher
• registrantid (from Crossref DOI prefix)

New master fields should support bibstems, ISSNs, or CODENS.

• notes_public should support plaintext strings.
• subject_areas should only support 4 digit ASJCs.

New publisher fields should only support publisherid.

All proposed fields (except notes_public) should support multiple values separated by semicolons.