Use single toolbar button for expand/collapse all annotations

[dstillman]

Instead of "Collapse All Annotations" and "Expand All Annotations", there should just be a single button that saves its state as a pref.

Could do this for B4 if you have time today.

[simon]

What's the intended behavior once #587 is implemented? When the snapshot first loads, should the button collapse all annotations unless all annotations are already collapsed? Or should we save the state of the button for each snapshot?

[dstillman]

I think when the snapshot loads, if none or some are open, the default state of the button should be to expand all--that seems more useful than collapsing all. If all are open, it should default to collapsing all. So probably doesn't need to use a pref after all.

[simon]

(In [3249]) - closes #999, Issues with removing highlighting on snapshots. I've tried my best not to introduce any regressions in the process, but I may have. In any case, this should work much better now.

• closes #1092, Defects with Sticky Note Annotations on the Wikipedia. We now put each annotation in its own iframe, eliminating CSS conflicts.
• closes #593, invert highlight color when highlighted text has a black background
• closes #588, Use single toolbar button for expand/collapse all annotations
• fix warning that annotations may only be opened in one window when annotation is not open in any windows
• fix annotation image oddities on OS X
• move annotation HTML and CSS to separate files
• add jsdoc documentation for annotate.js