Bug#210159: /usr/bin/apt-get: trigger error for --tar-only, --diff-only when not used with "source"

[Dan Jacobson <jidanni@jidanni.org>]

Package: apt
Version: 0.5.9
Severity: wishlist
File: /usr/bin/apt-get

Perhaps cause an error when --diff-only or --tar-only are used with
other choices than "source", e.g.
# apt-get --diff-only install grass
installs a 33.7MB archive ignoring --diff-only.