Add possiblity to compare 2 files and create nsh with diff

Hi, 

Thanks a lot for this fantastic tool. Very easy to use, perfect for me.

I want to compare 2 files : my bios and constructor bios and have possibility to show diff and export theses diffs into a nsh file. Do you think is it possible ?

Why tool doesn't support 0.3.x version of setup_var ?

Thanks again and have a good day !