Folder drag and drop support for the bookmark toolbar

Review Request #100220 - Created Dec. 18, 2010 and submitted

Yoann Laissus
- Bookmark folders can now be dragged and dropped in the toolbar.
- Drop a bookmark folder in the WebView no longer crash rekonq but open this folder in new tabs
- Fix some crash when a single bookmark is dropped in the WebView (incorrect URL)
- Port the drag icon to IconManager

Andrea Diamantini
I trust your code and testing it seems working well, but in ONE occasion: dropping one url from a subdir does NOT work.
  1. Thanks for testing. This patch only add drag and drop support for root folders. Drag & drop support for subfolder items is planned for a next patch.
Andrea Diamantini
Ok, merge it in master then :)