-Support inputting expressions that span multiple lines
  in erl shell.
-Adding new keybindings:
  navigate up (ctrl+up)/(alt+up)
  navigate down (ctrl+down)/(alt+down)
  insert newline in middle of line (alt+enter)
  navigate top (alt+<)/(alt+shift+up)
  navigate bottom (alt+>)/(alt+shift+down)
  clear current expression (alt+c)
  cancel search (alt+c)
-Modifies the prompt for new lines to make it clearer
  that the prompt has entered multiline mode.
-Modifies the search prompt to support multiline statements.
-Including keybinding for opening editor on mac
  (option+o)/(alt+o)
-Redraw the prompt after continuing from jcl menu.

* raimo/empty-target-host/OTP-18543:
  Test empty hostname behaviour only for Unix
  Test empty target host name
  Pass empty hostname through to backend
  Change inet_parse:visible_string/1 to allow empty string

Add skip condition for network related issues (on OpenBSD).

function `dbg:stop_clear/1` is not documented in the API but was kept
for compatibility reasons. in this commit we make a step forward to
deprecating its use such that it will be eventually removed.

closes GH-6903.

On Windows, the functions sendmsg and recvmsg are not supported.
So, instead of letting the test framework 'catch' the 'notsup'
(which it does not in all cases), just skip.

OTP-18029

Tweaked to make it (maybe) run cleanly on OpenBSD.

On Windows, when looking up the empty hostname, one gets
the address of localhost.  On Unix one gets a failed attempt
to find an address of the top domain (".").

Change the test cases to verify the Unix behaviour on Unix.