[fmos]

Have you considered Zim (http://zim-wiki.org)? It seems to check all of your points. I'm using it heavily for all kind of notes that exceed two lines. It has some amazing plugins too (e.g. For organizing Todo items across the entire notebook).

[hypercluster]

Not OP but I've looked into Zim and other Wikis several times but I can't find a good editor for mobile (iOS).