define conf in the test program, not in puny.c

improve logs management

const-ify var + missing argument

puny_decode: set an error string

fix build

punycode: refactoring use the correct term "label" instead of "component" when speaking about the parts of a hostname. Also, fix the sizes for max hostname and label.

compiler warnings

use starts_with in puny.c

const-ify puny_decode (and add puny.c)