This changes:
=. a ?. =(b c) a c
into:
=? a =(b c) c
This also adds a few obvious changes in the vanes and in app/talk.hoon
to take advantage of this new rune.
This will cause many false positives (all apps reloaded on any mark change), but @cgyarvin says it's better than them drifting out of sync as they currently do.