QtIFW

Fix warning and handle file scheme like files better.

Calling setFileName() prints a warning if the path is reset
without calling close() before.
Convert the source path with file:/// scheme to local file.

Change-Id: Ie21e7e8ad8f76dbe1afc1843ff5bf7fb4598123a
Reviewed-by: Kai Koehne <kai.koehne@digia.com>