Add flag `--all`

[marcospb19]

If you want to sweep everything, you might want to run cargo clean instead of sweep.

But cargo-sweep can be used as a cargo clean that runs recursively in a folder full of projects, here's how you do it:

$ cargo sweep --recursive --time 0

I suggest we add a --all flag to remove the need of using --time 0:

$ cargo sweep --recursive --all
$ cargo sweep --all

[jyn514]

Hmm, this seems fine, I suppose. I would want to desugar it to --time 0 internally if we do support it.

[Max-Weissman]

Can I try taking this on?

[jyn514]

@Max-Weissman sure thing, go for it :)