PICARD-1346: Fix exception with move additional files

When multiple patterns for move additional files matched the same file an exception was thrown when attempting to move the files again after it already had been moved.

picard/file.py

@@ -442,6 +442,7 @@ class File(QtCore.QObject, Item):
                 file_names = filtered_names
             for old_file in file_names:
                 if pattern_regex.match(old_file):
+                    file_names.remove(old_file)
                     new_file = os.path.join(new_path, old_file)
                     old_file = os.path.join(old_path, old_file)
                     # FIXME we shouldn't do this from a thread!