Neurons can now be queried by annotation(s) and/or annotator.
Start and end date are now used in querying annotations.
Neurons can now be annotated from the staging area (selection widget).
Neurons can now be added to the selection table and annotated from the neuron annotations query widget.
Tracing: add requirement for annotation class and relation

The tracing part of CATMAID now explicitly needs a class named
'annotation' and a relation 'annotated_with' to be available for a
project.
Neuron annotations: allow multiple instances of widget
Neuron annotations: remove tagbox code

This code is currently not used, conflicts some recent changes in master
and has many superfluous bits.
Neuron annotations: use request queue for annotation queries
Neuron annotations: make annotation query backend more robust
Neuron annotations: style changes
Neuron annotations: override submit behavior properly
Neuron annotations: use request queue for adding annotions
Neuron annotations: fix typo causing wrong result IDs
Neuron annotations: make sure the correct relation is used for annotating
Neuron annotations: make server side work with request queue arrays
Neuron annotations: remove debug output and do style changes
Neuron annotations: display a list of annotations in result table
Neuron annotations: add tool bar icon
Neuron annotations: use jQuery tagbox CSS for query widget display

Only the layout is used, not the functionality, by using tagbox' CSS
classes.
Neuron annotations: support annotation removal out of query widget