keyserver.c (parse_keyserver_uri): Parse keyserver URI into a structure.
Cleanup for new "guess my keyserver" functionality, as well as refreshing
via a preferred keyserver subpacket.
show_prompt, keyserver_search_prompt, keyserver_spawn): Go to version 1 of
the keyserver protocol. This is a better design, similar to
--with-colons, that allows for keys with multiple user IDs rather than
using multiple keys. It also matches the machine readable pksd format.
Also use a prettier --search-keys listing format that can fill different
size windows (currently set at 24 lines).
