See now https://github.com/coq/bignums
 Int31 is still in the stdlib.
 Some proofs there has be adapted to avoid the need for BigNumPrelude.

Found 1 incompatibility in tested contribs and 3 times the same
pattern of incompatibility in the standard library. In all cases, it
is an improvement in the form of the script.

New behavior deactivated when version is <= 8.5.

There were three versions of injection:

1. "injection term" without "as" clause:
   was leaving hypotheses on the goal in reverse order
2. "injection term as ipat", first version:
   was introduction hypotheses using ipat in reverse order without
   checking that the number of ipat was the size of the injection
   (activated with "Unset Injection L2R Pattern Order")
3. "injection term as ipat", second version:
   was introduction hypotheses using ipat in left-to-right order
   checking that the number of ipat was the size of the injection
   and clearing the injecting term by default if an hypothesis
   (activated with "Set Injection L2R Pattern Order", default one from 8.5)

There is now:

4. "injection term" without "as" clause, new version:
   introducing the components of the injection in the context in
   left-to-right order using default intro-patterns "?"
   and clearing the injecting term by default if an hypothesis
   (activated with "Set Structural Injection")

The new versions 3. and 4. are the "expected" ones in the sense that
they have the following good properties:
- introduction in the context is in the natural left-to-right order
- "injection" behaves the same with and without "as", always
  introducing the hypotheses in the goal what corresponds to the
  natural expectation as the changes I made in the proof scripts for
  adaptation confirm
- clear the "injection" hypothesis when an hypothesis which is the
  natural expectation as the changes I made in the proof scripts for
  adaptation confirm

The compatibility can be preserved by "Unset Structural Injection" or
by calling "simple injection".

The flag is currently off.

This reverts commit b6db76517b9a7f21078ab59a0b8eeee6bfdf5ba7.

for the record binder of classes. This name is no longer generated
in the kernel but part of the declaration. Also cleanup the interface
to recognize primitive records based on an option type instead of a
dynamic check of the length of an array.