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.

* 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

* 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

The removal set now uses a red-black tree instead of an array on
large inputs, decreasing runtime complexity from `n*n` to
`n*log(n)`. It will also exit early when there are no more items
left in the removal set, drastically improving performance and
memory use when the items to be removed are present near the head
of the list.

This got a lot more complicated than before as the overhead of
always using a red-black tree was unacceptable when either of the
inputs were small, but this compromise has okay-to-decent
performance regardless of input size.

Co-authored-by: Dmytro Lytovchenko <dmytro.lytovchenko@erlang-solutions.com>

The removal set now uses a red-black tree instead of an array on
large inputs, decreasing runtime complexity from `n*n` to
`n*log(n)`. It will also exit early when there are no more items
left in the removal set, drastically improving performance and
memory use when the items to be removed are present near the head
of the list.

This got a lot more complicated than before as the overhead of
always using a red-black tree was unacceptable when either of the
inputs were small, but this compromise has okay-to-decent
performance regardless of input size.

Co-authored-by: Dmytro Lytovchenko <dmytro.lytovchenko@erlang-solutions.com>

* john/erts/minusminus_trapping/OTP-15371:
  Optimize operator '--' and yield on large inputs
  Inline erts_cmp
  Clarify a magical allocation size
  Fix trapping in lists:reverse/2

The removal set now uses a red-black tree instead of an array on
large inputs, decreasing runtime complexity from `n*n` to
`n*log(n)`. It will also exit early when there are no more items
left in the removal set, drastically improving performance and
memory use when the items to be removed are present near the head
of the list.

This got a lot more complicated than before as the overhead of
always using a red-black tree was unacceptable when either of the
inputs were small, but this compromise has okay-to-decent
performance regardless of input size.

Co-authored-by: Dmytro Lytovchenko <dmytro.lytovchenko@erlang-solutions.com>