Add function for utf-16 compression

[fxwiegand]

This PR adds a function analog to this one that compresses to utf-16 encoding. Our project would benefit from having this function available directly from the crate and hopefully others will too. Please let me know if you need any changes, more tests or even the decompress method for example.

Since char::from_u32 is still unstable (see rust-lang/rust#71763) it could take some time before this can be merged.

[adumbidiot]

Hi, thanks for the PR!

While the associated function char::from_u32 is not stable, the function std::char::from_u32 is. I'll be happy to merge this if you could make that small change.

[fxwiegand]

Hi, thanks for the PR!

While the associated function char::from_u32 is not stable, the function std::char::from_u32 is. I'll be happy to merge this if you could make that small change.

Oh that is good to know! I think everything should good now.

[adumbidiot]

Thanks!