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.

Hence, also rename (the old) `equiv_entails` → `equiv_entails_1_1` and
`equiv_entails_sym` → `equiv_entails_1_2`, and add `equiv_entails_2` for completeness.