[Feature Request] Add Support for Command Line

[BarelyAPrincess]

Forgive me if this is a feature already present or can be better accomplished through a different utility, but I think it would be great to add command-line support for Cyan. I use Cyan regularly to convert the book covers I make from RGB to CMYK for printing and it has worked flawlessly. However, since I love automation to speed up my life, I would like it if I could wrap Cyan in a shell script that would do all the heavy lifting for me. If I can find the time, I will attempt to fork and implement it on my own, but that will have to wait for a later time.