Optional dependency marked as non-optional

[Yamakaky]

https://lut.im/ymtK7rowOA/ptiIYH7gGXE8gXw3.svg
My crate doesn't have a direct non-optional dependency to dlib, objc, core-graphics, cocoa and core-foundation, but theirs dependencies are marked as non-optional.
https://github.com/Yamakaky/dcpu

[mrcnski]

My fork fixes this. We should move to that as a community -- not responding to Issues or PRs for over a year is not acceptable.