This is in preparation for coq/coq#9274.

Adding a hint without a database now triggers a deprecation warning in
Coq master (https://github.com/coq/coq/pull/8987).

Modify adequacy proof to not break the 'fancy update' abstraction. Modify fupd plainly interface and add new derived results.

This follows the proof at https://en.wikipedia.org/wiki/L%C3%B6b's_theorem#Proof_of_L%C3%B6b's_theorem

rename : affinely_persistently -> intuitionistically. Add lemma about monpred_at and intuitionistically.

Fixes #156

The old one is admissable.

Thanks to @jtassaro and @jung.

This is backwards-compatible; it desugars to a normal application on previous versions

sed -i 's/∀ᵢ/\<obj\>/g; s/∃ᵢ/\<subj\>/g' $(find ./ -name \*.v)

sed -i 's/absolute/objective/g; s/relative/subjective/g; s/Absolute/Objective/g; s/Relative/Subjective/g' $(find ./ -name \*.v)

Based on an earlier MR by @jung.

This change is slightly more invasive than expected: in monPred we were
using the embedding before the BI was defined. With the new setup, this
is no longer possible, because in order to make an instance of the
embedding, we need to know that `monPred` is a BI. As such, we define
`emp`, `⌜ _ ⌝` and friends directly in the model of `monPred` and later
prove that they are equal to a version in terms of the embedding.

As suggested by @jjourdan, and proved in the ordered RA model by @amintimany.

This should solve the paradox in #149.

In the same style as most of the BI lemmas, e.g. `or_mono`, `and_mono`, ...