Export widget: improve UI messages

- Fix missing path string substitution in error message when treenode
  archive directory is not writable
- Fix confusing verb tense for message indicating export is in process
Doc: update administration section to reflect current update procedure
Doc: link to administration section from TOC on front page
Doc: add section about SSL setup to administration setup
Grid layer: set and update SVG size properly

The SVG has to be as big as the stack's view.
Remove CSS extraction from stack and overview map

Refactor the overview map to defer to CSS to set the map container size
and compute overview scale from the computed style instead of parsing
CSS rules. Remove unused CSS extraction from the stack view. Since these
were the only dependents on rule order in `stack.css`, remove rule order
warning comments.

Progress towards removing `getPropertyFromCssRules`.
Remove CSS extraction from slider and cropping

Refactor slider widget to not depend on extracted CSS properties. The
slider handle is now positioned as a percentage of the slider, instead
of in absolute pixels. Slider and handle margins are now controlled by
CSS rather than through JS styling. Non-breaking spaces used as
positioning were removed from slider labels accordingly. CSS extraction
was also removed from sliders in the cropping tool. Since these were the
only dependents on rule order in `slider.css`, rule order warning
comments were removed.

Progress towards removing `getPropertyFromCssRules`.
Tools: remove CSS rule extraction

Remove `getPropertyFromCssRules` and helper function `getCssRules`
because they create brittle dependence on the inclusion order and rule
order of CSS files.
Fix dash key zoom out on Firefox

Since Firefox 15 the dash key (between '0' and '=') has emitted key code
173, rather than 109, which is now only used for the numpad minus key.
(Chrome emits 189 for the dask key.) This change supports this key for
zooming out in the navigator and tracing tool.
3D viewer: create floor as sub-divided plane instead of lines

As it turns out, rendering quads (and triangles) is much faster than rendering
lines. This improves the performance of the 3D viewer quite a bit.
Connectivity widget: remove TableTools

Replace the TableTools DataTables extension with a simple click handler
to export connectivity tables as CSV. Remove the TableTools library.

Revert the majority of fc6ad191e4c46bc7ba43d1c6642fae5e2a4fc1c0
Connectivity widget: use selector for checkboxes

Use a selector to select all checkboxes instead of fixed table and row
child indices. Thresholding partners rearranges the order of table
children, which was breaking the select all checkbox.

Closes acardona/CATMAID#748.
Review widget: fix minor syntax issues
Review widget: don't pass key event if not needed

When a review key (i.e. Q, W or E) is pressed, the tracing tool passed the key
event to to the review widget. This isn't actually needed and complicates
things. This commit removes this parameter from the respective functions and
replaces one use with a dedicated argument.
Review widget: queue selection of next segment after pending requests

The selection of the next segment depends on client side information about the
review state of all nodes of all segments. To select the next segment based on
the latest information, the selection is now queued after currently pending
requests. This makes sure all single node review requests have been handled
before.

This is related to issue #743. Though it isn't clear yet if this was the only
problem that could lead to this behavior.
Review widget: move comment and remove unneeded user name override

By default, the anonymous user (i.e. when no-one is logged in) has ID -1. Back
when the review system didn't support multiple users, -1 as a user ID was also
used to mark a treenode as not reviewed. This has changed and is not done
anymore, because there is now a separate review table containing only actual
reviews. Therefore, we don't need this name override for non-reviewed treenode
entries anymore. Besides this, the name also had a typo in it.
Review widget: simplify marking node as reviewed slightly

The line was called no matter what, so we can move it up as well and remove two
appearances of it.
Review widget: warn if sections are skipped

When moving through a node in a review segment, warn if the node just
reviewed is more than one section away from the current node.

Closes acardona/CATMAID#744.
Replace growl alert library

The previous growlAlert library limited the clarity of feedback
provided to users by alerts in several ways:

  - Messages queued one at time, leading to confusion about what action
    an alert is responding to if multiple alerts created cumulative
    delay.
  - The same color for all alerts equivocates action confirmation,
    warning, and error notification. When performing tasks routinely
    generating notification alerts, such as reviewing, users can
    desensitize to alerts and inadvertently ignore warnings.
  - The library provided no easy way to mitigate either of the above
    issues, even through callbacks.

BlockUI has a primitive growl alert functionality, but it has similar
limitations.

Replace the growlAlert library with jQuery growl, which is of similar
size but has desktop growl-like stacking alert queues and supports alert
styling. Match alert titles to contextually style most existing alerts.
Replace legacy direct calls to the growlAlert library with calls to the
more commonly used `growlAlert` global helper.
Improve several alert messages (minor)