[getdns-api] Nearly-final version of the API available

[Paul Hoffman]

... at http://www.vpnc.org/getdns-api/

The changes since the last one are:

- Fixed the second argument of getdns_context_set_context_update_callback to use uint16_t instead of getdns_return_t

- Got rid of getdns_var_t because it was used inconsistently

- Added getdns_context_set_timeout() to section 8.3

-  Added a list of extensions at the beginning of section 3

- Added answer_ipv4_address and answer_ipv6_address to the top level of replies_tree; also made the names there optional


With respect to two recent threads here:

- I am not going to add a "prime the cache" function. It would add a lot of complexity to the API for very narrow use, and it has some security considerations that I think are intractable: do you really want one application to directly affect the results seen by another application instead of everything coming from the DNS itself?

- The API handles TSIG between when the API is acting as a stub resolver, but not at other places. I'm still pretty unclear how this API would sensibly be used for regular AXFR and IXFR; if some more functions get added to a later version of the API, this could be addressed then.


I'm pretty sure this is baked enough for the organizations who want to start implementing it to do so. If I don't hear anything by early next week, I'll slap a "done" label on it.

--Paul Hoffman