Tracing layer: add button to toggle slice controls

Adds a toolbar button to the tracing layer that toggles visibility of
the layer sliders and scale benchmark, complete with terrible icon.
Closes acardona/CATMAID#434.
Stack: add control to toggle slice controls

Adds a button in the lower left of the stack view, similar to the
overview toggle, that toggles visibility of the layer sliders and scale
benchmark. See discussion in acardona/CATMAID#434.
Revert "Tracing layer: add button to toggle slice controls"

This reverts commit 957331916f33c89e01f77a408a252775d0bdc31d.
Overview: fix missing semicolons (minor)

Also remove dead commented code.
Stack: fix slice control toggle pointer CSS (m)
Stack: better stack control toggle icon

Replace the stack control toggle icon with one from @tomka more
consistent with other stack UI and indicating toggle state.
Merge branch 'issues/434-slice-control-toggle'
Extract neuron name service into separate file

Since NeuronNameService is modular and well-decoupled from the rest of
utils.js, extract it to its own file.
Neuron name service: semicolon cleanup (minor)
Doc: make pip update requirement on Ubuntu 12.04 a note
Doc: also install Distribute like NumPy prior to pip-frozen modules

A newer Distribute module is needed to install matplotlib, which is a
dependency specified in the pip-frozen file. Therefore, it has to be
installed before calling "pip install -r pip-frozen", just like NumPy.
Doc: update repository URL and add graphismagick dependency

Thanks to @kotowicz for suggesting theses changes. This commit changes
the documentation so that HTTPS is used for the CATMAID repository URL
(instead of GIT protocol). Also graphicsmagick is added as a dependency
to make it possible to run the suggested "gm convert -list format"
command).

Closes #726.
Doc: use current year in copyright notice
Doc: update contributors
Doc: refer to configuration.py when showing an example of admin URL
Doc: remove obsolete reference to dj/ subfolder
Neuron name service: unregister specific skeletons

Allow clients to unregister specific skeletons from the neuron name
service rather than unregistering completely. Calling `unregister` with
a single argument preserves the original behavior of unregistering the
client from all skeletons and from update notification.
Neuron navigator: uncheck 'select all' when search is used

Closes #618
Neuron name service: handle bad unregistrations

Always treat `skids` as an array of skeleton IDs in `unregister`
(unlike `managedSkeletons`, which uses IDs as object keys), and do
nothing for requests to unregister a skeleton ID which was not
previously registered.
Fix neuron name display in canvas topbar

A previous commit broke the active neuron name being displayed in the
topbar when selecting a node (a115b9808b1443280f667a44be204f1945fb31ef).
This fixes that regression and updates neuron name display in the topbar
to use the neuron name service. Manual updates of the topbar made
redundant by this change are removed, including `updateNeuronNameLabel`.

Closes acardona/CATMAID#738.