[Feature Request] Support multi-line snippet

[jiamingz42]

[nfedyashev]

That would be nice indeed!

What I noticed is that if you manually add "\n" to your command in ".config/pet/snippet.toml" then those snippets outputs as a multi-line command instead.

Still investigating why I can't use "native" multi-line input for new pet snippets. It would have been really cool if pet respected editor setting in .config/pet/config.toml and used a specified editor instead of a single-line input that it currently has.

[ofey404]

I've made a PR for multi-line support #161. Basic feature is usable.