Move command line stuff to separate package and avoid fsnotify dependency?

[georgefst]

Personally, while I think Diagrams.Backend.CmdLine is cool, in six and a half years of using this library quite regularly, I only ever used it on day one. I prefer to just call ghcid or ghciwatch for this sort of thing, not least because code caring about its own source location seems brittle. So it's always felt like something which belongs in a separate library.

This has become a concrete issue for me when targeting Wasm, since fsnotify doesn't build there. This is the only module which relies on fsnotify.

Obviously this would be a breaking change, but it'd have a one-line fix. And I wouldn't imagine this module is seeing serious production use.

[byorgey]

Oh, good suggestion. I'm all for getting diagrams to build with Wasm.

I will look into some options. Perhaps one less-impactful change we could make that would still achieve the goal would be to keep Diagrams.Backend.CmdLine but simply remove the looped rebuilding feature (and hence the fsnotify dep). With stuff like ghciwatch, ghcid, entr, etc. it's not too hard to set it up externally. I'd rather not more/remove Diagrams.Backend.CmdLine entirely since there's a lot of stuff in there besides the looped rebuilding and I think it would break a lot of workflows.