- cxt-unique-objset-implies-same-class
- cxt-unique-objset-implies-least-nonnull
added clsmap-cxt-capmap/null, to handle the special shared target.
As result, I need to change quite a few theorems about clsmap-cxt-capmap,
like clsmap-cxt-capmap/U-inversion. I still need to add a few more.