Update subject scheme map w/ revised version from @keberlein
Merge pull request #1796 from infotexture/feature/docsrc-subjectscheme

Fix `docsrc` subject scheme map #1795
Move configuration options to runtime properties #1799

* generate-debug-attributes
* processing-mode
Simplify preprocessing filter configuration
Clean constant use
Remove old Java command line tool #1800
Use Commons IO #1803
Remove outdated `files.txt` listing for #1804

Fixes #1804
Merge pull request #1805 from infotexture/feature/filelist

Remove outdated `files.txt` listing for #1804
Remove docsrc in favour of separate repo
Add documentation from docs repo
Clean PDF plug-in stylesheet

* Remove obsolete comments
* Add datatypes
Fix build script to work with new docs build
Merge remote-tracking branch 'upstream/develop' into develop