Implement std::fmt::Display

[sfleener]

Currently, SmartString only implements std::fmt::Debug. This makes it difficult to use as a drop-in replacement for String, especially in format_args contexts such as println:

use smartstring::alias::String;

let s = String::from("hello");
println!("{}", s);

This adds in a simple implementation of std::fmt::Display. This also removes the manual implementation of std::string::ToString, as that has a conflicting blanket implementation for types that implement Display.

[bodil]

Wow, weird omission on my part. Thanks for the impl.

[djc]

Was also looking for this. Are you planning on pushing this out into a release soon? :)

[bodil]

It's in crates.io now.

[djc]

Thanks!