* dgud/stdlib/unicode-binary-bug/ERL-777/OTP-15428:
  unicode_util did not handle binary input data correctly

RFC3339 mentions in paragraph 5.1 that if certain conditions are
fulfilled, then sorting date and time strings results in a
time-ordered sequence. One of the conditions is that the strings must
have the same number of fractional second digits. This commits makes
sure this is indeed the case.

An external fun could inadvertently suppress warnings for
unused variables, such as in this example:

    bug() ->
        BugVar = foo(),
        if true ->
            fun m:f/1
        end.

There would be no warning that `BugVar` was unused.

The bug was introduced in ff432e262e652, which was the commit
that extended external funs to allow variables.

https://bugs.erlang.org/browse/ERL-762

gc_zwj sent binaries recursivly to gc_extend/3 which didn't handle
can't handle them.

ERL-777

* maint-18:
  Updated OTP version
  Prepare release
  Optimize operator '--' and yield on large inputs

Conflicts:
	OTP_VERSION
	erts/doc/src/notes.xml
	erts/emulator/beam/erl_alloc.types
	erts/emulator/beam/erl_bif_lists.c
	erts/vsn.mk
	lib/stdlib/doc/src/notes.xml
	lib/stdlib/vsn.mk
	make/otp_version_tickets
	otp_versions.table

* john/erts/OTP-18.3.4/minusminus_trapping/OTP-15371:
  Optimize operator '--' and yield on large inputs

* maint-20:
  Updated OTP version
  Prepare release
  Optimize operator '--' and yield on large inputs

Conflicts:
	OTP_VERSION
	erts/doc/src/notes.xml
	erts/emulator/beam/erl_alloc.types
	erts/emulator/beam/erl_bif_lists.c
	erts/vsn.mk
	lib/ssl/doc/src/notes.xml
	lib/ssl/vsn.mk
	lib/stdlib/doc/src/notes.xml
	lib/stdlib/vsn.mk
	make/otp_version_tickets
	otp_versions.table