Add Tipue Search

Successor to #60. Rebased and updated.
Ah, I see. Okay, yeah, this makes sense. I don't actually remember why I went with this approach, I think it was just the way the original PR started it. Since the theme needs to include Tipue this makes sense. My only small concern would be with having .js files being jinja2 templates - that could get confusing. It would also then make sense to place it under the Tipue directory and not at the top level. I'll do this.