Use Decorations for rendering marker views

When the react editor is there, it uses decorations. 

This can likely be made much cleaner. But I wanted to minimize changes as we still need to support the old editor. 

This breaks the result highlighting in themes, which is super annoying. All the themes need to be updated to use different selectors. 

Someone try it out! For me, it feels sooo much faster on large searches.  I suppose you have to have an updated theme, which I will do tomorrow.

Ref #145