[r-t] Minor principles (MUG)

[Alexander Holroyd]

This looks better!  Can you remove some more bobs as well?  (The one I
sent had considerably less than a naive q-set procedure would produce, I
think).

Pabs wrote:

> We don't need to have round blocks with a pair behind to join them
> together, so some of the half-lead calls can be avoided:
>
> 720 MUG Minor