Add support for figuring out dependencies of a package

[Shardion]

This would need gentoolkit. Disable by default, set a build-time flag and add a USE flag to the ebuild (which would add a dependency for gentoolkit)?

[Phate6660]

It would still show up in the help as (for all I know), you can't selectively add/remove things from it with clap.
However I can disable the respective code for it from being compiled if the appropriate feature isn't set, so yeah I can do that.
I would need to update the crate first (as the ebuild depends on it), but when I do, yeah I'll add a use flag for it which will automatically pull in gentoolkit and set the feature.

[Phate6660]

Crate has been updated. Haven't updated the ebuild yet though, I'm gonna wait a bit to do that cause I'm lazy.
But hey now you can install the latest version from crates.io so that's good.