[getdns-api] Remove IDNA functions from getdns?

[Willem Toorop]

Greetings getdns API spec developers,

Currently the API defines two functions for IDNA 2008:
getdns_convert_ulabel_to_alabel() and getdns_convert_alabel_to_ulabel()

In our implementation, those are (more or less) direct mappings to the
underlying idna_to_ascii_8z() and idna_to_unicode_8z8z() functions from
the GNU IDN library.  Applications that need to do IDNA conversions,
might just as well use those functions from libidn directly instead of
using the getdns facades.  Because of those two functions our library
has a dependency on libidn, but does not add any extra value on top of
that library.

Because of this, I propose to remove getdns_convert_ulabel_to_alabel()
and getdns_convert_alabel_to_ulabel() from the API specification.

What do you thing?

-- Willem