Add support for Óbudai Egyetem

Add option to hide favorites in menu.

The "leckekönyv" module was removed and replaced with a total menu rewrite:

Replaces the dropdown menu (from the previous Neptun interface) with a horizontally laid-out menu bar and removes the search textbox.

It also revamps the favorites management, removing the completely unnecessary 8-item limit. Favorites are still stored in Neptun, but in an incompatible format, which will overwrite previous favorites. Any URL can be added as a favorite.

(release notes translated from Hungarian using LLM)