Implement modular specifications from the HOCAP paper

See merge request FP/iris-examples!5

Had to slightly tweak (strengthen) stack3's spec for that

Using concurrent runners

- Get rid of the timelessness condition for Q
- Allow Q to depend on the argument as well on the result
- Make it more easy to apply the lemmas by using IntoVal in the public
  API

- Implement the concurrent runners library

- Changed the shared bag specification to allow the predicate `P` to
  depend on the bag itself -- this is needed for the `isRunner`
  invariant: since the bag is *part* of the `Runner` class, the bag is
  constructed/allocated before the `Runner` itself is construted; but
  we want the bag invariant to depend on the `Runner` instance.

Fix a file broken due to wp_binop changes

See merge request FP/iris-examples!7

- Fix a file broken due to wp_binop changes

Add more examples from the lecture notes.

See merge request FP/iris-examples!6

Make EqType more realistic

See merge request FP/iris-examples!4