Install binary globally

[zamith]

I have multiple toolchains, including some nightly for a specific date, and when I install a binary it gets installed to that toolchain's bin directory, which means I would have to add a bunch of directories to my PATH.

Does it make sense to be able to download and compile a crate with a specific toolchain, but installing it to ~/.cargo/bin?

[brson]

@zamith I think I'd rather stop overriding $CARGO_HOME, and let all toolchains share it. This is what multirust-rs is going to do.

[zamith]

@brson Is that already possible, or is it something you wish to do?

[brson]

@zamith It's a change I'd like to make.