This is more consistent with the definition of the extension order, which
is also defined in terms of an existential.

It is not non-expansive, so not a function we should use.

They are redundant because frac is discrete.

fix typo

@jung good?

See merge request !2

With Coq 8.6, you can no longer have intro patterns that give more names than
the constructor has.  Also, patterns with too few names are now interpreted as
filling up with "?", rather than putting the unnamed parts into the goal again.

Furthermore, it seems the behavior of "simplify_eq/=" changed, I guess
hypotheses are considered in different order now.  I managed to work around
this, but it all seem kind of fragile.

The next compilation failure is an "Anyomaly: ... Please report", so that's what I will do.

This generalization is surprisingly easy in Iris 3.0, so I could not
resist not doing it :).

This makes stuff more uniform and also removes the need for the [inGFs]
type class. Instead, there is now a type class [subG Σ1 Σ2] which expresses
that a list of functors [Σ1] is contained in [Σ2].

In most cases it is a temporary whose name is useless and just
clutters the error message.

This commit reverts cdce49a7, which turns out to be no longer useful,
and which I thus no longer wish to maintain.