Torrent records wiped when disc filled

[thomas.bevan@gmail.com]

All torrent files a wiped if, while downloading a torrent, the disc is filled.

Downloaded data is not damaged but the torrent files seem to be lost

[andar]

This should be fixed now. We save to a temp file, sync to disk, then move the file into the proper filename. If the disk is full, it should fail writing to the temp file and the state file should not be overwritten.