digicademy/svsal: SvSal v1.4.0

This is a maintenance and bugfix release.

Maintenance:

• new separation of TEI research data, derived research data (and intermediate formats), and app logic

Fixes:

• reading view: rendering of gaps & blank pages
• API: special cases with query parameters & passage IDs
• multiple read/write issue with corpus creation
• longstanding bug with HTML rendering, which required double renderings for yielding correct fragment URIs
• analysis of a TEI work's fragmentation depth
• removed stale index files
• smaller fixes in pages' texts, wordings, usability