Core reference and Libraries reference entries share the same template

Because there's a single template to build all of the reference pages, the Library reference pages have the wrong left-nav option selected (Reference and not Libraries). Also, they can't have a custom message at the top of the page about the Javadoc. I think this requires digging into java-generate and rebuilding the Java classes.

In addition, the non-core Libraries from the Processing Foundation (Video and Sound) can't have a separate header message. They link to the Libraries Javadoc, but the code isn't there. Thinking about this more, we could probably build those Javadocs and add them while the rest are built.

Inizia esaminando il template condiviso delle pagine di riferimento e l’entry point java-generate menzionato nell’issue, quindi traccia il modo in cui vengono ricreate le classi Java. Il lavoro è completato quando le pagine Library selezionano Libraries nella navigazione a sinistra, supportano messaggi Javadoc personalizzati e le pagine Video e Sound gestiscono i propri link Javadoc o i Javadocs generati come previsto.