Add super versions of cargo commands

[ideasman42]

This searches up the parent directories for the 'outer' most Cargo.toml, useful for building the entire project from a nested crate.

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Note that I had problems using this plugin as-is.

The paths as reported in the quickfix window were relative to the Cargo.toml, not the pwd.

While the build worked, cycling through the errors didn't open the proper files.

This PR passes the Cargo.toml location to cargo, and adds support for building the parent-most Cargo.toml, which I needed when using creates in subdirectories of other crates.

[timonv]

I've yet to see a project where toml's are nested, do you have an example? I usually just work with different versioned crates. Also, I could imagine that if your build pipeline is that complex, you might need a Makefile.

[ideasman42]

For an example see: https://gitlab.com/ideasman42/raster-retrace/tree/master this is something supported by Cargo for quite some time.

[timonv]

Looks good to me! Just needs the conflicts resolved.