batch-rename: Use tmp filename in the case of filename "loops"
Errors can occur when batch renaming files if a new filename matches an existing filename. Reordering the files does not solve this problem if the filenames contain loops (ex. A -> B & B -> A). Instead of reordering the files, give any problematic files a temporary name and handle them after the rest of the files have been renamed. GNOME/nautilus#1443