Some compare function are not exported

[yjhmelody]

I want to directly use specific types of comparison functions, such as boolean::compare, but I found that they are not exported.
But their scalar version such as boolean_compare_scalar are exported.

Should we make the following mods be pub?

mod boolean;
mod primitive;
mod utf8;

pub mod boolean;
pub mod primitive;
pub mod utf8;

[jorgecarleitao]

Thanks! fire it away :) Could give it a quick look to make sure that they are documented? The mod would probably also benefit from a docstring on the top to denote that they are for.

[yjhmelody]

Some of them are undocumented, some are, and so are the scalar versions.