Rename traits and types to be the same between `std` and `tokio`?

[TheLostLambda]

This one is purely to do with style, so it's only if you think it's a good idea.

Essentially, I've found it a bit unusual to have Std* types everywhere in my project that doesn't use tokio — I reckon (though this is just my intuition), that most people using this library would be using either std or tokio and that mixing is rare? In that case, I think lines like this:

use process_wrap::std::{StdChildWrapper, StdCommandWrap, StdCommandWrapper};

Might look better like this:

use process_wrap::std::{ChildWrapper, CommandWrap, CommandWrapper};

If you did ever have to mix those two types in the same module, then I think it would be perfectly reasonable to just:

use process_wrap::{std, tokio};
// Then refer to the types as:
std::ChildWrapper, std::CommandWrap, std::CommandWrapper
// And
tokio::ChildWrapper, tokio::CommandWrap, tokio::CommandWrapper

There used to be a clippy lint for this (https://rust-lang.github.io/rust-clippy/master/#module_name_repetitions), but it's pretty pedantic, so, again, I think this is up to your preference!

It saves characters most of the time, and only adds two (::) in the worst-case.

[passcod]

Yes, I think that was historical-as-of-#23 due to the std version having a Child wrapper, which made things confusing. I wouldn't want to present the std::Whatever / tokio::Whatever style in documentation because I think that's confusing when std and tokio are crates of their own right, but that can be left up to the user.

If you want to make another PR with this it'd be welcome, otherwise I can do that later this week.

[TheLostLambda]

Should hopefully be a pretty easy change, so I'm happy to put in a PR for it!