Wordpress has a feature where you can compare an article with the one in history, it will show what changes are made and differences.
It would be great to cs-cart to view custom changes in the code. It will be helpful to view against files in the repository and against updates.
Here is a screen shot (sorry for the size but I had to fit everything):
Notice how well it can detect changes done in the middle of the test…
Would adding the ability to do a three-way diff with analysis detail down to the character level meet your needs?
Bob