Remove several dependencies

[RandomInsano]

It seems that the visibility crate was to just make certain functions public to test. I figured the easier thing to do would be to change the function visibility to just be for the crate and this should make sure they can't be used by other crates (the CLI included) effectively meaning they should by dropped for being unused.

The only real reason I did this is that I want to use Hematita on Windows 7 (yes, it's over 13 years old) and I had thought that some of my compiler errors being thrown by some dependencies could be fixed by removing them. Sadly no! But hopefully things compile a lot faster. That's a win too.