drag-and-drop multiple image upload functionality & crossREF lookup tweaks

• Upload multiple key figures/tables simultaneously
• Slick drag-and-drop images functionality
• Various crossREF lookup article metadata and formatting enhancements (courtesy of @JoeAmmar, thanks again!)
  • Added ?mailto in crossref api calls (to ensure we're not rate limited)
  • Automatic author name formatting (i.e., I Cheung, L Campbell, EP LeBel, SS Smith, ST Smith, SR Smith, ... , & JC Yong)
  • Automatic citation count extraction (WoS)
  • Automatic year extraction coverage based on whether it's a published study or not
  • Automatic extraction of preprint_url (if available)
  • Automatic extraction of abstract text (if available)
  • Convert article title from title case to sentence case (incl. capitalizing first word of subtitle)
  • Ensure subtitle is extracted and concatenate title and subtitle
  • And various other minor capitalization and formatting tweaks