Neuron navigator: save space in neuron node display
Neuron navigator: factor out user table creation

Putting the creation of the user list table into its own function allows an
easier re-use of it. This is needed, because a (filtered) user table should be
displayed in the neuron node.
Neuron navigator: show user who locked neuron in neuron node

The user who locked a neuron is the one who annotated the node with an
annotation called "locked". For the sake of consistency, a data table has been
used here as well.
Neuron navigator: style and consistency renaming changes