[BT] Slightly fixed code style for first Reset() overload.
[BT] More nice refactoring for TorrentFilesModel.
[BT] RolePath -> RoleFileIndex.

And store in ColumnPath BTW.
[BT] Better siblings calculation.
[BT] Use std::find_if in HandleFileActivated().
[BT] Don't handle file activations in addition dialog.
[BT] Avoid TorrentFilesModel::gotEntity().
[BT] Separate columns for addition mode & dynamic list.
[BT] Use siblings in {Mark,Unmark}Selected().
[BT] Avoid magic numbers in TorrentFilesModel.
[BT] Fixed indents in TorrentFilesModel.
[Util] Refactored common ModelItem methods to ModelItemBase.
[BT] Removed excessive include.
[Azoth] Use passed parameter to lambda.