Also, put stuff in a section.

Also, make our redefinition of done more robust under different
orders of Importing modules.

change statement of inv-open lemmas such that they do not force the invariant, and the 'inner step', to appear right next to each other

Also do some minor clean up.

Introduce the notion of "Frame Shift Assertions", and use to prove the rules about inv and auth at once for pvs and wp

Yeah, the name is horrible... but on the plus side, I think it should be possible to show that atomic triples and atomic shifts are also frame shift assertions, and then we get all this stuff for them for free.

Actual proofs will end up using own and inv, and none of the notions defined in ownership.v