Unfortunately, this meant I lost all of the built-in autocomplete and hinting features, so I spent a few hours constructing building a .tags file for the Unity 5 Scripting API for Geany. You can find it here: https://github.com/DThought/unity-tags
I thought I'd share it in case other people found it useful and could be added to http://www.geany.org/download/extras#tags.
Great! what about adding it to the wiki? http://wiki.geany.org/tags/start
Thanks, it's been added. Didn't realize the wiki was publicly editable, though I guess that's what a wiki is for.
Cheers ~ Ethan