Removed wizard.

This removes the 'wizard' functionality, which was designed to let
annotators swiftly move through a text, sentence by sentence. The wizard
as implemented leads to significant code duplication, and it has always
been quite fragile and plucky about navigation. A sensible annotator
would, in any event, circumvent the wizard and work with multiple
windows in order to work efficiently.

The idea is to remove the wizard for now and extend the sentences view
with more single-page-app-like functionality. That should eliminate the
need for a separate wizard and at the same time significantly enhance
annotator productivity.