Suggestion from Gregory Malecha, forall lemmas suggested by Robbert & Ralf,
proof scripts from me.

Example include Equiv, Dist, Op, Core, Valid, ValidN and Unit.

The previous hints used eapply. The new hint now use refine. These two
tactic use a different unification algorithm, which result in
different behavior with respect to canonical structures.

The refine tactic is followed by shelving all the remaining goals,
which correspond actually to existential variables.

In particular, in RustHornBelt, the version using apply is unable to
find the canonical structure of heterogeneous lists.

also add `wand_entails'`, which was used in some earlier version of these proofs

Tej Chajed authored 4 years ago and Ralf Jung committed 4 years ago

Fixes #404

Makes it possible to use several logical steps for one logical steps, in a way which can be controlled by ghost state.