It is based on type classes and can it be tuned by providing
instances, for example, instances can be provided to mark that
certain expressions are closed.

And now the part that I forgot to commit.

Also, give all these global functors the suffix GF to avoid shadowing
such as we had with authF.

And add some type annotations for clarity.

I added a new typeclass "inGF" to witness that a particular *functor* is part of \Sigma. inG, in contrast, witnesses a particular *CMRA* to be in there, after applying the functor to "\later iProp".
inGF can be inferred if that functor is consed to the head of \Sigma, and it is preserved by consing a new functor to \Sigma. This is not the case for inG since the recursive occurence of \Sigma also changes.
For evry construction (auth, sts, saved_prop), there is an instance infering the respective authG, stsG, savedPropG from an inGF. There is also a global inG_inGF, but Coq is unable to use it.

I tried to instead have *only* inGF, since having both typeclasses seemed weird. However, then the actual type that e.g. "own" is about is the result of applying a functor, and Coq entirely fails to infer anything.

I had to add a few type annotations in heap.v, because Coq tried to use the "authG_inGF" instance before the A got fixed, and ended up looping and expanding endlessly on that proof of timelessness.
This does not seem entirely unreasonable, I was honestly surprised Coq was able to infer the types previously.

this makes it slightlymore annoying to use because we have to elliminate the box. one more reason to have a proof mode ;-)

* Put level of the triple at 20, so we can write things like
  ▷ {{ P }} e @ E {{ Φ }} without parentheses.
* Use high levels for P, e and Φ.
* Allow @ E to be omitted in case E = ⊤.

This avoids ambiguity with P and Q that we were using before for both
uPreds/iProps and indexed uPreds/iProps.

* These type classes bundle an identifier into the global CMRA with a proof
  that the identifier points to the correct CMRA. Bundling allows us to get
  rid of many arguments everywhere.

* I have setup the type classes so that we no longer have to keep track of the
  global CMRA identifiers. These are implicit and resolved automatically.

* For heap I am also bundling the name of the heap RA instance. There always
  should be at most one heap instance so this does not introduce ambiguities.

* We now have a "maps to" notation!

Whenever clients get this stuff out of invariants, this is much more convenient for them, compared to applying timelessness themselves.
On the other hand, this makes the test proofs slightly more annoying, since they have to manually strip away that later. I am not sure if it is worth having separate lemmas (well, tactics, soon) for that.
Eventually, we should have a tactic which, given "... * P * ... |- ... * \later^n P * ...", automatically gets rid of the P.

We only use wp_value in the end if the resulting goal is yet
another wp. Otherwise we may not be able to do a final view
shift (as observed by Ralf).

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

The rationale is that, just like the always lemmas about uPred and the frame-preserving updates for maps and iprdos, the versions with the ' are the "more specific" versions, hard-coding more assumptions in the shape of their conclusion.