That way, we do not have useless type annotations of the form
"v : language.val heap_lang" cluttering about any goal.

Note, that we could decide to eta expand everywhere (as we do for ∀
and ∃), and use the notation "WP e {{ Q }}" for "wp e ⊤ (λ _, Q)".

newline before the first context" and "shuffle 0-width spaces around so
they are distributed more evenly"

This reverts commits e3c56f9e and
7fc1124c, which are workarounds for
Coq bug https://coq.inria.fr/bugs/show_bug.cgi?id=4675

Also, this commit fixes the levels to avoid parantheses.

Pros:
* It does not matter how editors render the 0-width space, everything is always aligned
* In ProofGeneral, there is no more incorrectn indentation of the first line

Cons:
* There is an empty line between the bar ending the Coq context, and the first Iris hypothesis

It is not a library; it does not contain code, but instead is a core
part of heap_lang.

This reverts commit 3cc38ff6.

The reverted pure hypotheses and variables appear in the wrong order.

Since strip_later is doing a good job stripping laters in the conclusion,
these tactics are thus no longer needed. Also, wp_finish now properly
converts the result in a primitive viewshift in case it is not a weakestpre.

And introduce more useful variants with a wand.