Fix failed to resolve 'paste' crate & migrate to pastey

[Keinsleif]

Using command_writers_and_readers! macro outside of kira causes failed to resolve: use of undeclared crate or module paste error.

command_writers_and_readers! macro generates code that uses paste::paste! macro. But, paste is not always included in external crate's dependencies. That cause Failed to resolve error.

You can solve this problem by adding "paste" in external crate dependencies. But adding crate not used directly is little strange.

This PR solve this problem by extern paste crate by pub use ::paste in lib.rs and use paste package via $crate metavar.

I found similar issue in paste crate repository.
dtolnay/paste#69

Also, there is the post describes about solution.
https://users.rust-lang.org/t/proc-macros-using-third-party-crate/42465/4

[tesselode]

I'm seeing that the paste repo is archived - does anyone know of any good alternatives?

[Keinsleif]

I found pastey, the fork of paste.
pastey pvovides simple migration solution by replacing paste with pastey.

paste = { package = "pastey", version = "*" }

But migrating paste to pastey is included in #142

Should I add this migration to PR?

[tesselode]

sure, go for it! i'll merge this in after

[Keinsleif]

added migration to pastey.

[tesselode]

thank you!