port "cask" -- installing prebuilt binaries

[Ken Cunningham]

I wasn't imagining a variant for binary-only installs. If a port can be built, we should build it.

But for things we can't build, (like Zoom or Microsoft Word) installing a binary is the only option and some ports of this type seem to be what people are submitting recently.

This is fine -- some work to maintain -- but I was just wondering if we might coalesce around a scheme to make it obvious somehow to users that these were different animals than our usual ports.

K