Parsing error due to a bug

[jvictorchen]

The national number of phone number +33 07856952 should be 07856952. But the code is returning 78569522 as the result. This is caused by a bug in line

potentialNationalNumber := builder.NewBuilder(normalizedNationalNumber.Byte())

The problem is that we are creating potentialNationalNumber from normalizedNationalNumber.Byte(), which is a pointer. So any change in potentialNationalNumber will also change the value of normalizedNationalNumber.

I will submit a PR to address this issue.