WIP: use SciJava for views.

Does not work yet.
There are some misfits with methods that should be in two interfaces....
Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Fix the view discovery & integration.

We now use the SciJavaPlugin 'visible' annotation to decide what shows
up in the GUI menu or not.
Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>