Multi-pass required to correctly unidecode

For some cases it needs several passes to completely convert to ascii. Take this example:

var unidecode = require('unidecode')
var s = 'Rocío Martín-Valero'; // there is a hidden - appearing after both Ã's if you paste in console!
console.log(unidecode(s)) // prints RocÃo MartÃn-Valero (removes that hidden -), but still not ascii
console.log(unidecode(unidecode(s))) // 2 passes to print RocAo MartAn-Valero

Here is the hexdump of the above string:

00000000 52 6f 63 c3 83 c2 ad 6f 20 4d 61 72 74 c3 83 c2 |Roc....o Mart...|
00000010 ad 6e 2d 56 61 6c 65 72 6f 0a |.n-Valero.|
0000001a

So it seems it can't convert the 2 sequences `c3 83` and `c2 ad` that are back to back.

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