IPP core protocol in pure Go Library (RFC 8010)

 The goipp library is fairly complete implementation of IPP core protocol
 in pure Go. Essentially, it is IPP messages parser/composer. Transport
 is not implemented here, because Go standard library has an excellent
 built-in HTTP client, and it doesn't make a lot of sense to wrap it here.
 .
 High-level requests, like "print a file" are also not implemented,
 only the low-level stuff.