Make clipboard a feature

[FortStatement]

Running cargo install jless on my dev servers currently fails because it doesn't have libxcb, which is required by the crate clipboard. I was thinking maybe it could be a default feature which I could disable explicitly, or maybe check for libxcb in build script.

I can implement it if it's deemed a good idea @PaulJuliusMartinez :smile:

[LukasDoesDev]

Wayland clipboard support would be awesome too

[kellpossible]

Even better would be to detect availability of clipboard at runtime instead of crashing or requiring a custom build?