Multivalues/multiple return

[darrylabbate]

E.g.

a,b = 1,2      // a = 1, b = 2

fn f() {
    return 1,2,3
}

x,y,z = f()    // x = 1, y = 2, z = 3

Note that this would technically be a "breaking" change with the way commas are currently parsed in expression statements.