Add strip leading whitespace/indent option

[MadLittleMods]

It would be nice if you were slicing a block of code that was all indented in, to have an option that strips the common amount of whitespace from each line in order to perfectly left align it.

Maybe use the npm strip-indent package or this Python recipe for block formatting as some inspiration.

        foo: function() {
            var a = 1;
            return a;
        }

to

foo: function() {
    var a = 1;
    return a;
}

[nighto]

+1, that would be very nice. :+1: