Inconsistent code indentation

[3c1u]

Indentation is mixed/inconsistent in file image_test.c.
https://github.com/hmdlab/frame_diff/blob/master/src/image_test.c#L278-L299

Try clang-format. (e.g. https://github.com/3c1u/dotfiles/blob/master/.clang-format)

[Xilorole]

We've also tried formatting the whole script, however running automatic corrections didn't entirely work. As you can see in the codes, the initial code has uneven spaces, and line breaks to write the descriptions to make students comfortable to understand.

I was not sure why this code was not changed for years. To have clear codes and have the same informative commenting structure, we'll work on both the script understandability and consistency. Thank you for the recommendation!