Show favicon for about:treestyletab-group tab correctly on Firefox 22 and later (#521)

Because URIs like "chrome://treestyletab/skin/group/group-icon#-moz-resolution=16,16" doesn't work, if the chrome URL is defined by "override" directive.
Detect new tabs opened from content scripts correctly (#517, #510)
Update sample script for Greasemonkey to test multiple links
Suppress error while the last tabs is dragged over the tab itself
Find "insert before" reference tab and move the dragged tab to the upper level correctly, even if the parent tab has no next sibling.

This should work for cases like #297.
Add a string bundle entry "closeTabsToTheEnd_vertical" for the menu item in the vertical tab bar.

See also #529 and https://bugzilla.mozilla.org/show_bug.cgi?id=866880
Update label of "Close Tabs to the Right" menuitem to "Close Tabs to the Bottom" in the vertical tab bar #529
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Deactivate debugging flag
Output more messages for debugging
Don't shrink tab bar when user selects background tabs #526
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Support getShortcutOrURIAndPostData() on Firefox 25 and later.

See also:
https://github.com/piroor/treestyletab/issues/524
https://bugzilla.mozilla.org/show_bug.cgi?id=846635
Open new tab from DragIt ( https://addons.mozilla.org/firefox/addon/dragit-formerly-drag-de-go/ ) as a child of the current tab. #523
Print more information in the debugging mode
Restore tree structure for "undo close tab" feature #525

It was a regression on 0.14.2013052901.
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