Revert "TEMP: Don't remove 'zone.' prefix"

This reverts commit f4745322b03138fd1a334b6261be3c6d0060c317.
Revert "TEMP: Never add 'routers' option"

This reverts commit 7259777e8f064d79013b595cf64f096af5703f5a.
Revert "TEMP: If ALLOW_KNOWN, allow members of Ctnr-Range"

This reverts commit ace00c67715497a64364d0cf179c91d9af863997.
Revert "TEMP: Build Workgroup even if it has no interfaces"

This reverts commit 7133c85dc9d4a4db7968bb863dfd57c5861741ea.
Print 'known-clients' instead of 'known clients'

It's what's in the dhcpd.conf(5) man page and it appears to be more
commonly used.
Change Ctnr build function name