Add missing QTreeWidget::dropEvent to d'n'd atempt occuring in same location.

Remove 'Overwrite attempt' dialog as obsolete. Now moving item, e.g. from folder to same folder, will just make it the last child of the folder.
Drag'n'Drop fixups.

1. Proper event handling
2. Allow folder moving
3. Allow moving into folders
Merge pull request #682 from Gelmir/rss_dnd_sameplace

Repopulate the feed tree after drag&drop to same location
Merge pull request #683 from Gelmir/rss_proper_drag_move

Fix Drag/Move event in RSS widget
Properly rename torrents, when index is moved out of current filter model or changes position inside filter model while rename window stays open
Merge pull request #727 from Gelmir/rename_on_index_changes

Properly rename torrent which changes position in filter model