Scintilla v5.5.7 officially requires at least GCC v9, but if it's
only the charconv header that's required from newer releases, v8.1
will probably do as well. We assume so until proven wrong.

* It requires a forced refresh on startup (even though that should be the
  default). Otherwise, it wouldn't print the info line correctly.
* Redirect stdin and pass it to newterm() to fix key queuing.
  Probably necessary for supporting ncurses on NetBSD as well.
* Avoid doupdate() if screen is too small: fixes crashes for very
  small windows.
* Updated Scintilla: There were some implicit typing assumptions,
  that are broken by this platform.

Esp. mention the new OBS repositories.

* Greatly improved usability as a scripting language.
* The command is in DEC TECO, but in contrast to DEC TECO, we also
  support string building constructs in ^A.
* Required some refactoring: As we want it to write everything verbatim
  to stdout, the per-interface method is now teco_interface_msg_literal()
  and it has to deal with unprintable characters.
  When displaying in the UI, we use teco_curses_format_str() and TecoGtkLabel
  functions/widgets to deal with possible control codes.
* Numbers printed with `=` have to be written with a trailing linefeed,
  which would also be visible as a reverse "LF" in the UI.
  Not sure whether this is acceptable - the alternative would be to strip
  the strings before displaying them.
* Messages written to stdout are also auto-flushed at the moment.
  In the future we might want to put flushing under control of the language.
  Perhaps :^A could inhibit the flushing.

* Many terminal emulators won't have the status-line terminfo capabilities
  but still support OSC-0 escape sequences for setting the window title.
  This affects the real XTerm, rxvt-based and many emulators that claim to be
  XTerm via $TERM (e.g. GNOME Console).
* It seems we can safely assume that any emulator with $TERM beginning with "xterm" or
  "rxvt" does in fact have OSC-0 or at least ignores it.
  The number of whitelisted emulators might be extended later on.
  This way, we don't have to add another ED flag.
* We still give precendence to the to_status_line/from_status_line capabilities
  if they are in terminfo.

* These are famously in DEC TECO-11, but also in Video TECO.
* The implementation is tricky. They need to use lookahead states,
  but this would be inacceptable during interactive execution.
  Therefore only if executing from the end of the command line
  `==` and `===` are allowed to print multiple values.
  The number is therefore also not popped form the stack immediately
  but only peeked. It's popped only when it has been decided that
  the command has ended.
* This may break existing macros that use multiple `=` in a row
  to print multiple values from the stack.
  You will now e.g. have to insert whitespace to separate such `=` commands.

* In this case we always save the given buffer and never the current Q-Register.
* The current Q-Register is only saved without any numeric argument.
  The same semantics make sense for <EF> so that Q*EF closes the current buffer
  even when editing a Q-Register.
* This variant is present in Video TECO.

* While it doesn't directly change the buffer's contents in bytes,
  a subsequent write would result in a different file on disk,
  so it is consequent to remind the user of saving or discarding changes.
* Will also fix :EX after changing the EOL mode.