Refactor the document search interfaces, as discussed on the mailing list.

Merge the search in normal mode and the type-ahead in a search bar that appears on the bottom of the page view. This should work nicely.

In presentation mode, add a small floating search toolbar that takes care of searching during the presentation mode, on document request. This is not working yet, but basically most of the work is done.

Please test and report any problems you find.