v3.19.0

Fixed:

• typos in the web OCR-D Web API, #199
• typo in the OCRD-ZIP spec, #203
• fix bagit-profile URL, #205

Changed:

• Drop Ocrd-Manifestation-Depth and disallow fetch.txt bagit mechanism, #182
• Drop unclear has_docker attribute in discovery response in OCR-D Web API, #201

Added:

• Parameters can now be described with most JSON-Schema constructs, #206, OCR-D/core#848