* raimo/kernel/gen_statem-progress/OTP-14114:
  Make code_change/4 optional
  Implement fallback for terminate/3
  Clarify code_change and callback mode change
  Stop pampering with stacktraces
  Clean up timer handling
  Remove event timer optimization
  Clean up timer handling
  Reduce number of loop variables hence code mass
  Optimize by using async cancel_timer
  Bugfix: callback mode not cached after code change
  Implement repeat_state and repeat_state_and_data
  Correct type checking function for action {next_event,,}
  Change arity of type to init_result/1

zip: Fix bugs ERL-348 and ERL-349

OTP-14246

Make sure that zip:extract() and zip:create() closes the zip
file if there is an error.

ERL-349

filename: Add safe_relative_path/1

OTP-14215

As of committing this branch maps:fold/3 calls maps:to_list/1, which
means that the time and memory needed for printing maps is not always
proportional to the size of the generated deep list of characters.

Add safe_relative_path/1 to guard against directory traversal
attacks. It either returns a shorter path without any ".." or
"." components, or 'unsafe' if an ".." component would climb
up above the root of the relative path. Here are a few
examples:

  safe_relative_path("a/b/..") => "a"
  safe_relative_path("a/..") => ""
  safe_relative_path("a/../..") => unsafe
  safe_relative_path("/absolute/path") => unsafe

The returned path can be used directly or combined with an
absolute path using filename:join/2.