bug#25426: [PATCH] in net-utils.el several DNS query functions now take optional name server argument; also, `dig-program-options' added

[Andrew Robbins]

- In a git-clone'd "lisp/net/net-utils.el" I modified several
interactive DNS-querying functions (nslookup-host,
dns-lookup-host, run-dig) to allow specifying a particular name
server to use where before you couldn't. This is possible
non-interactively as well as interactively with a prefix argument.

- Also, a new variable `dig-program-options' is defined to allow
users to set options for use with `run-dig'. This is in line with
the current `nslookup-program-options' and
`dns-lookup-program-options' and is necessary for the new
definition of `run-dig' to function.

- The `run-dig' function no longer needs the auto-loaded
`ffap-string-at-point' function, removing one dependency on
ffap.el 

For all users, and especially those unaware of the changes, there
should be no discernible difference in functionality when used
exactly as before.

My changelog and diff are attached.

changelog_net-utils
Description: Binary data

diff_net-utils
Description: Binary data