Neuron search: force 'annotated_with' relation if annotator is given

The annotation search has an 'annotated by' field (only 'by' in the widget),
which was so far only used to check if an annotated entity was related in any
way to another entity and that this relation was created by the user. To only
take annotations into account, the 'annotated_with' relation is now required.
Neuron dendrogram: add option to disable warning if selected node is hidden

If one wants to go quickly though a neuron (e.g. during review) and the
dendrogram is open for it, the warnings can get annoying easily. The newly added
option allows to disable it.
Neuron dendrogram: maintain selection after option change