Moved Iris specific stuff into a utility file.

TODO: fix in-place merge function.

Also weaken some specs by adding laters.

- Allow for binders in protocols.
- Model protocols in CPS style using the COFE solver.
- Change the channel methods so they do not mention sides.
- Lots of refactoring.
- Generalize the `list_sort` example.
- Move stuff to stdpp/Iris.

Maintaining the same example twice is just too much work.

- Put code and proofs of examples in a single file.
- Rename encode/decode to avoid conflicts with encode/decode (of the countable class) in stdpp.
- Remove useless imports.

commit a96494d62639ca14449d90c3a510c3a63a28fc07
Author: Jonas Kastberg Hinrichsen <jkas@itu.dk>
Date:   Tue May 7 18:39:41 2019 +0200

    Finalized List sort example, and introduced list encodings

commit 1b9fc4de897a5ea15c0e9a11b4ace407adda02ad
Author: Jonas Kastberg Hinrichsen <jkas@itu.dk>
Date:   Fri May 3 15:28:21 2019 +0200

    WIP List sort example

commit 4ce5eb98585f25daa6b5682cdc6ab34a192f2b69
Author: Jonas Kastberg Hinrichsen <jkas@itu.dk>
Date:   Fri May 3 11:18:07 2019 +0200

    WIP list sort example