So I've never used sed before and I accidentally ran it on all of the files in the code directory, including the fonts and libraries.zip, and it ended up modifying those files as well.  How do I revert changes for just a few specific files?  I have not committed them yet (although I have committed everything else), so how to I get the old versions back in my working directory?  I can't test to see if I broke anything else without them :(