Wrong imports, doesn't compile on case sensitive filesystem

[Zvezdin]

The line include "./Sha256Input.circom"; of sha256var.circom uses the wrong case to import the file, which is committed with a lowercase s in github. It compiles on a mac but would fail on most other filesystems.

[noway]

Thanks for the bug report @Zvezdin. I would really appreciate a PR with the fix otherwise will try to get to it some time. Cheers.