Added Run variant

[rroels]

Having a Run variant allows users to execute ("run") the produced
binary with Crtl+Shift+B (or CMD+SHIFT+B on OSX).

[dbp]

Is that supposed to be ".$file_base_name" - ie, is the dot supposed to be there?

[rroels]

Yes, on Linux/OSX you would execute a binary like this (e.g. ".foo" to execute binary file foo)
EDIT: no, you are right, there's an error here, it should be ./foo

[dbp]

Hmm. That's not true, at least for linux (what I use). Do you mean "./foo"? .foo looks for a binary named ".foo" in your path.

[rroels]

You are absolutely right, I was confused for a moment there. It's because I always do:
rustc --out-dir=bin foo.rs

So in my sublime-build I have ./bin/$file_base_name

But I thought it would be bad to force the output in a certain folder, so I changed it to the root folder, and killed a slash in the process.

[dbp]

Looks good!