Refactor getBookmarkItem() and getHistoryItem()
(related to #7)
Add support for any places <tree>
(#7)
Correctly handle places <tree> inside tab in Firefox <= 3.6
(#7)
Ignore errors about places <tree> in Firefox 3.0
(works for <tree> inside tab only in Firefox 3.5+)
(#7)
Mark compatible with Firefox 29.0a1 and SeaMonkey 2.26a1
Update copyright year