Improvements to the signup and password-reset pages
Fix display of events title
Retooling of search hit highlighting (fixes #407).

 - Highlighting no longer attempts to munge a whole chunk of Html,
   it now has to be applied individually to fields
 - Added a new interface for a `Highlighter` with a highlight method
   and made `SearchHit` implement this, which allows using a dummy
   highlighter when there's no hit available
 - Still a bit WIP...