This change also modifies the ndhc/ifchd wire protocol slightly. The
new protocol doesn't overload the ':' character as a key:value separator
and a statement separator. Instead ';' is now used as a statement separator.
The new format allows for more robust error-checking and reporting, and it
greatly simplifies the parser. Old versions of ndhc/ifchd will not work
properly with ones compiled after this commit.
The 'domain' and 'search' keywords in resolv.conf updates are now used
more precisely. The first domain in an update is the 'domain', and the
subsequent 5 domains are 'search' domains.
There are also supporting cleanups that pass struct ifchd_client pointers
to functions instead of passing index values.
This commit is large, but it cannot really be broken up into smaller
chunks since the changes are dependent on each other.
