Search no more...
Here's a replacement for Vanillas default search, but by now it is only a preview and therefore, when you enable it, nothing will change.
Please see the description on the addon page in order to get it working. I planned to be ready before christmas but I guess I have no chance reaching that goal and so here is what I've got by now.
Maybe it doesn't scale at all and no one can use it in a live environment. But it was a a nice coding experience nevertheless.
And being able to search for +word1 -word2 posted by userX in discussion between 2014/10/01 and 2014/11/15 is fun!