Reorder Requires so that we do not depend of Export bugs.

See merge request iris/iris!313

The general idea is to first import/export modules which are further
than the current one, and then import/export modules which are close
dependencies.

This commit tries to use the same order of imports for every file, and
describes the convention in ProofGuide.md. There is one exception,
where we do not follow said convention: in program_logic/weakestpre.v,
using that order would break printing of texan triples (??).

Add `iStopProof` tactic

Closes #265

See merge request iris/iris!311

This commit closes issue #265.

We have these instances for all other logical operations too to support
setoid rewriting in both directions.

fix typo in the docs

See merge request iris/iris!310

Iris 3.2 release notes

See merge request iris/iris!309

Lemmas for list cmra

See merge request !308

Simon knows why ;)

Add `big_sepL2_swap`

See merge request iris/iris!307

Lemmas for big ops commuting with updates

See merge request iris/iris!305

Add `head_prim_fill_reducible_no_obs`

See merge request iris/iris!306