Implement "reactions" #9
Description
There needs to be a way for users to react to various things.
Maybe this could just be done as a note? Notes can now be attached to a set of objects now, but they are user specific, so a fit.
Big disadvantage: as long as ObjC has no inline-content support, this would have to create a file for each reaction. And notes that are not attached to a project are stored in a single namespace within LSAttachmentPath, i.e. they are not clustered by ID range. Leading to huge directories (some w/ 100k notes).
Maybe we could fix this in ObjC (use clustered storage, w/ global fallback OR inline notes).
Reactions could be emoji-data based and just store the :name: as used in many systems. E.g. it would be a note w/ just a :name: content (and maybe a special text_content_type).