Fix issue when you rename the "root item" in the "Add New Torrent" dialog
and uncheck "Create subfolder", it will create the subfolder with the
renamed name.
Fix PropertiesWidget first folder is expanded after app restart.
Strip root folder if torrent was added via magnet link.
Fix crash when you get name of torrent without metadata.
In addition to the current tooltip, which shows color legend, if user
holds the Shift key during hovering we show another tooltip which
contains a table of contents for the piece under the moue cursor. The
table lists file sizes and names. If the cursor points to a part of a
file which spans several pieces, those pieces are highlighted.
