drag and drop service for extraction from files

[WolfgangFahl]

Is your feature request related to a problem? Please describe.
There should be a web-based service using a drop-target zone to allow drag&drop (or at least upload) of files of different formats. For a start e.g. text,PDF, maybe Doc, docx and other office formats.

Describe the solution you'd like
stepwise process:

• extract text from document
• process potentially location references
• create a list of results in a selectable format e.g. csv, json, xml, sparql

Describe alternatives you've considered

• RESTFul interface
• Content Negotiation
• Command-Line Tool

Additional context

• https://github.com/greyli/flask-dropzone as a potential library/tool to use
• https://github.com/WolfgangFahl/pyFlaskBootstrap4 for synergy with the ConfIDent and other projects