Added PairUp/PairDown.
Tweaking maps, mostly.
Getting type classes out of the viewing business.
The great leap forward for 2.11; backward for 2.10.

Huge strides in finding the right implicit balance. In 2.11.
In 2.10 everything has gone to hell. Rather than let that hold
me up overmuch I'm pushing it as-is and will figure out what
to do about 2.10 later.