Code for handling unicode/punycode name conversions v2

Opening new PR for clean commenting
[ Quoting <notifications@github.com> in "Re: [dns] Code for handling unicode..." ]
>> +	{"A-B", "a-b"},
>> +	{"AbC", "abc"},
>> +	{"я", "xn--41a"},
>> +	{"zя", "xn--z-0ub"},
>> +	{"ЯZ", "xn--z-zub"},
>> +	{"إختبار", "xn--kgbechtv"},
>> +	{"آزمایشی", "xn--hgbk6aj7f53bba"},
>> +	{"测试", "xn--0zwm56d"},
>> +	{"測試", "xn--g6w251d"},
>> +	{"Испытание", "xn--80akhbyknj4f"},
>> +	{"परीक्षा", "xn--11b5bs3a9aj6g"},
>> +	{"δοκιμή", "xn--jxalpdlp"},
>> +	{"테스트", "xn--9t4b11yi5a"},
>> +	{"טעסט", "xn--deba0ad"},
>> +	{"テスト", "xn--zckzah"},
>> +	{"பரிட்சை", "xn--hlcj6aya9esc7a"},
>
>Check my new test please.

Ack. Can't sign in because I forgot my phone. See here goes it goes:

     punycode.go#L32: if s[len(s)-1] == '.' {
this crashes on an empty string.

     #L47
uncode -> unicode in the comment. It would also extent the comment to say
what happens when the strings isn't in punycode format.

     #L120
Why does preprune mention a different RFC than the one mentioned in the package
documentation? Should we mention that RFC there too?

And maybe rename encodeBytes to encode and the same thing for decodeBytes?

For the rest LGTM.


>https://github.com/miekg/dns/pull/129/files#r17539300
/Miek

-- 
Miek Gieben