Not hooked up to be called yet.

Sorry for the noise, downstream custom builders.  Please adjust.

We are not going to use them, at least in the foreseeable future

Also, uncomment code again, just "if (0)" it out, so it doesn't get stale again.

We should hang those off somewhere else. For now, the unused ones can go.

For run-time checking.

Also makes hb-ot-shape call morx for now instead of GSUB... Just for testing.

Untested, but compiles.

Also makes hb-view to use 8 bits of subpixel precision and shape at
requested size, instead of always shaping at upem and scaling results.

Like hb-view, but prints out buffer contents.

The output format is kinda cryptic.  Suggestions welcome.