I had missed the one in lower section.

This reverts commit 202bb737e3deabfebee683266f4b7c42781eb521.

* hasse/stdlib/rfc3339_datetime/OTP-14764:
  stdlib: Add RFC 3339 functions to module calendar

Allow installing multiple instances of sys debug function

This commit solves a bug which allowed installing {Fun,State} as sys debug function even if Fun was already installed. This happened in the case when the current State of the debug fun was undefined.

Also, the new format {Id,Fun,State} of debug functions can be installed, allowing multiple instances of the same fun.

[stdlib/sys.erl] Fix sys module's debug statistics not including the out message count when using gen_server:call/2.

OTP-15047

Functions for converting between RFC 3339 strings and system time
are added.

Options are lists, but we are considering using maps instead. If we
change, it will happen after Erlang/OTP 21.0-rc1 is released.

* hasse/stdlib/calendar_systemtime/OTP-13413:
  stdlib: Add system time functions to module calendar

Inspiration from module lager_format.

Also some improvements of Unicode handling.

io_lib:format/3 and io_lib:fwrite/3 are new functions. The
representation of the options is a list, but we are considering using
a map instead. If we change, it will happen after Erlang/OTP 21.0-rc1
is released.

* raimo/stdlib/gen_statem-dev/OTP-14015:
  Fix after feedback
  Improve pointer to User's Guide
  Fix after feedback on 'When to use'
  Add a 'When to use' section
  Fix timeout parsing and doc feedback
  Improve doc, change images to .svg
  erl_docgen: Implement width in image tag
  Update User's Guide and pointers to it
  Improve error reasons from state enter call