XWiki is a powerful Java-based programmable wiki system, more of a hybrid wiki/cms.  To be honest, in an ideal world I'd rather have continued to custom-implement my site in Lisp, but I had to balance that against time available, and after evaluating several options I ended up going with XWiki for now.

Installation is straightforward on Debian, just following the relevant XWiki docs.  The most involved part was setting up "short URLs" - losing the odd javatastic /xwiki/bin/view url prefix.  Note from time to time xwiki versions have introduced new url segments for special purposes (e.g. asyncrenderer), keep an eye on the path exclusions as documented upstream.

Syntax Highlighting

XWiki apparently uses Pygments (via Jython) for syntax-highlighting in the {{code}} macro, so the available languages are those supported by Pygments: http://pygments.org/docs/lexers/

Breadcrumb tree menu

Is handled in hierarchy_macros.vm, if you want to change it to display more than 10 entries in the dropdown. https://forum.xwiki.org/t/increase-number-of-entries-in-breadcrumb/903/4

Java Compatibility

At time of writing (2019), XWiki LTS is not yet compatible with Java 11 / post- Java 8.  It's straightforward to use Java 8 for now while Java 8 itself is still supported of course, just worth keeping an eye on.