Multi does not detect renamed files in status

[teknomunk]

Currently, when you rename a file, multi status will show a deleted file and a new file instead of a renamed file.

To reproduce:

echo "test" > test.txt
multi commit -m "A commit"
mv test.txt test2.txt
multi status

Current output:

	deleted:  test.txt
	new file: test2.txt

Expected output:

	renamed: test.txt -> test2.txt