[Feature] Shuffle mangled identifier alphabet

Example code:

function foo(bar, baz, bak, bos){
  return bar + baz * bak - bos;
}

Current output:

function a(b, c, d, e) {
    return b + c * d - e;
}

Output with shuffled alphabet:

function k(u, z, p, b) {
    return u + z * p - b;
}

[sanex3339]

Probably, the best way to do it - is to create the new mangled-shuffled (that extends mangled generator) identifier names generator. Because if I want to change base mangled generator - a huge amount of tests will fail because the order of variable names changes. But I need to know the correct order in the tests.

I can stub base order but here so many places where I have to stub it, so the best way is to create the new generator instead.

mangled-shuffled sounds correct?

[sanex3339]

Released 1.5.2 with few fixes