Make "structopt" dependency optional

[adumbidiot]

The structopt dependency seems to be only used for the binaries. It would be nice if it could be disabled if this engine was used as a library. Maybe it could be put behind a cli feature flag or similar and enabled for the binaries only?

[jasonwilliams]

@adumbidiot that sounds fine to me, is this something you wanted to look at?

[adumbidiot]

Yeah sure

[Razican]

Another option would be to separate the crate into two: boa and boa-cli, in the same workspace. This would allow for differentiating the CLI from the library itself, and not require features: each crate would have its own dependencies, and share them if compiled together.

[jasonwilliams]

@Razican sounds interesting, would it still be easy to develop against the CLI when working against the lib? Ive not split 2 crates in the same project before

[Razican]

@jasonwilliams it should be easy, yes. Both crates would be in the same repo, with a Cargo.toml especifying the workspace. The Cargo.lock file would be at a workspace level. A huge example with multiple crates can be seen with diesel.

I can do a PR this week to see how it would look like, but I think it should be fairly easy.