* Turns out that on SunOS/OmniOS the ncurses port does not ship with
  a ncursesw pkg-config file, but the ncurses file is for a version,
  that does contain widechar support as well.
* Instead of adding yet another recursive PKG_CHECK_MODULES() call,
  we now use the AX_WITH_CURSES() macro, which is probably more robust.
  This should at least fix ./configure on OmniOS.
* It also adds a number of feature C macros, that could be useful to
  check in the future.
* At the moment, we strive to support all X/Open-compatible Curses
  libraries, but both enhanced and color functions are required.
  Therefore plain SVr4 Curses is not supported.
* source: https://www.gnu.org/software/autoconf-archive/ax_with_curses.html

* The previous convention of !* ... *! are now true block comments,
  i.e. they are parsed faster, don't spam the goto table and allow
  embedding of exclamation marks - only "*!" terminates the comment.
* It is therefore now forbidden to have goto labels beginning with "*".
* Also support "!!" to introduce EOL comments (like C++'s //).
  This disallows empty labels, but they weren't useful anyway.
  This is the shortest way to begin a comment.
* All comment labels have been converted to true comments, to ensure
  that syntax highlighting works correctly.
  EOL comments are used for single line commented-out code, since it's
  easiest to uncomment - you don't have to jump to the line end.
  This is a pure convention / coding style.
  Other people might do it differently.
* It's of course still possible to abuse goto labels as comments
  as TECO did for ages.
* In lexing / syntax highlighting, labels and comments are highlighted differently.
* When syntax highlighting, a single "!" will first be highlighted as a label
  since it's not yet unambiguous. Once you type the second character (* or !),
  the first character is retroactively styled as a comment as well.

* They are used at runtime only by the GTK port.
* Their existence can cause problems if OS-specific build systems
  have to clean these files from the staging directory afterwards.
  This was the case on FreeBSD where the committer refused to remove
  these files after installation.
  In the official FreeBSD port, we therefore currently ship the
  PNG icons unnecessarily.
* They are now installed and shipped only on GTK builds.

* We don't actually have to negate ^S results after FK.
  For deleting the matched pattern, you can use ^YD or -^SD.

* this works by embedding the SciTECO parser and driving it always (exclusively)
  in parse-only mode.
* A new teco_state_t::style determines the Scintilla style for any character
  accepted in the given state.
* Therefore, the SciTECO lexer is always 100% exact and corresponds to the current
  SciTECO grammer - it does not have to be maintained separately.
  There are a few exceptions and tweaks, though.
* The contents of curly-brace escapes (`@^Uq{...}`) are rendered as ordinary
  code using a separate parser instance.
  This can be disabled with the lexer.sciteco.macrodef property.
  Unfortunately, SciTECO does not currently allow setting lexer properties (FIXME).
* Labels and comments are currently styled the same.
  This could change in the future once we introduce real comments.
* Lexers are usually implemented in C++, but I did not want to draw in C++.
  Especially not since we'd have to include parser.h and other SciTECO headers,
  that really do not want to keep C++-compatible.
  Instead, the lexer is implemented "in the container".
  @ES/SCI_SETILEXER/sciteco/ is internally translated to SCI_SETILEXER(NULL)
  and we get Scintilla notifications when styling the view becomes necessary.
  This is then centrally forwarded to the teco_lexer_style() which
  uses the ordinary teco_view_ssm() API for styling.
* Once the command line becomes a Scintilla view even on Curses,
  we can enabled syntax highlighting of the command line macro.

This release is mainly for the upcoming FreeBSD package.

* We cannot call it "." since that introduces a local register
  and we don't want to add an unnecessary syntactic exception.
* Allows the idiom [: ... ]: to temporarily move around.
  Also, you can now write ^E\: without having to store dot in a register first.
* In the future we might add an ^E register as well for byte offsets.
  However, there are much fewer useful applications.
* Of course, you can now also write nU: instead of nJ, Q: instead of "." and
  n%: instead of "nC.". However it's all not really useful.

* This way the search mode and radix are local to the current macro frame,
  unless the macro was invoked with :Mq.
  If colon-modified, you can reproduce the same effect by calling
  [.^X 0^X ... ].^X
* The radix register is cached in the Q-Reg table as an optimization.
  This could be done with the other "special" registers as well, but at the
  cost of larger stack frames.
* In order to allow constructs like [.^X typed with upcarets,
  the Q-Register specification syntax has been extended:
  ^c is the corresponding control code instead of the register "^".