I've finally gotten around to uploading the CVS repository onto SourceForge. You can browse or download the repository using the links under the "Code" menu.
Thanks also to those who have submitted patches and bug reports. I will integrate these into the project shortly.
The new version of diffh has a lot of bug fixes, so should produce better output, not give segmentation faults for large inputs, and stop telling you the file is invalid when it isn't.
In particular, files with unicode, files with no newline at the end, and input from diff -U0 now work properly.
Diffh is now on SourceForge! The version now available for download is source only, but can be compiled for POSIX or Windows without hassles. It's perfectly functional so if you want to take the pain out of reading diffs, download it now!