* libgui/module.mk: remove empty variable OCTAVE_GUI_EDITOR_MOC

* libgui/src/module.mk: Generate "moc-console-lexer.cc" only when building with
QScintilla. Sort files alphabetically in lists.

* libgui/src/qt-interpreter-events.cc: Include "console-lexer.h" only when
building with QScintilla.

* libgui/src/console-lexer.h: Use name for inclusion guard that differs from
the one used in m-editor/octave-txt-lexer.h.

* configure.ac: Fix typo in value of BUILD_EXTERNAL_LIBXERBLA. There should be
no functional change because currently it is only checked whether this variable
is non-empty.

* main-window.cc (main_window): call focus_command_window only if
  event loop is idle by using a single shot timer

* main-window.h: make focus_command_window a public slot

* command-widget.cc (command_widget): open temp files for redirecting
  stdout and stderr, setup a file system watcher for signals on changes
  to these files;
  (~command_widget): close and remove the temp. files;
  (insert_interpreter_output): use the style as second argument
  (print_stream): add new contents of temp. files for stdout and stderr
  to the end of the terminal contents;
  (notice_settings): set the terminal preferences to the new lexer of
  the console;
  (console): create and set new lexer;
  (new_command_line): use prompt style for the prompt;
  (execute_command): use second command line argument for the style;
  (append_string): use style as second argument and style the added
  text accordingly;

* command-widget.h (console) append_string with second argument for style,
  (command_widget): now with destructor, new method print_stream,
  insert_interpreter_output with second argument for style, new class
  variables for temp. file descriptors and file system watcher

* console-lexer.cc/h: new lexer derived from QScintillas default lexer
  for styling the terminal output, styles used so far: Default, Error,
  and Prompt

* gui-preferences-cs.h: new constants for error and prompt colors

* libgui/src/module.mk: new files console_lexer.cc/h

* qt-interpreter-events.cc (display_exception): interpreter_output_signal
  with second argument for the style, here Error style

* qt-interpreter-events.h: interpreter_output_signal with second
  argument for the style

* terminal-dock-widget.h: interpreter_output_signal with second
  argument for the style

* .github/workflows/make.yaml (alpine): Alpine Linux 3.20 has recently been
released. Apparently, their LaTeX packages are more fine-grained now. Install
more packages that are needed to build the documentation.

* pt-idx.cc (tree_index_expression::end_pos): Fix handling of struct
field names.

* configure.ac: Check if C and Fortran compilers accept -fexceptions flag. Add
that flag to XTRA_CFLAGS and FFLAGS, respectively, if available.

* .github/workflows/make.yaml (ubuntu): Add Ubuntu 24.04 runners to CI matrix.
Remove Ubuntu 20.04 runners from CI matrix.

* bar.m: Use double quote in preference to single quote.  Use two spaces after
code and start of single-line comment.  Don't use continuation ellipsis when
defining matrices which have an EOL semicolon indicating a row break.

* bar.m, barh.m: Add BISTs for data output, plotting, listeners, and update
functions. Add xfail BISTs for axis labels and horizontal baseline parameters.

* Add input validation check for barh call with no input arguments and
call print_usage.  Update BIST to check for error message.

* hist.m: Add check for the distance between max and min Y value when
calculating the bin locations.  If distance is less than 20*eps, use
calculation for distance = 0 to avoid error where X value separation is
smaller than eps and appear non-unique.  Add BISTs to check for no error
with small Y values with and without a specified number of bins.
* NEWS.9.md: Addd note about fix to hist.m line under Improvements and Fixes.

It is a known problem with Qt that terms like "signals", "slots", and "emit"
can conflict with other libraries using those identifiers. So far, Octave
has not had that problem, but to allow for potential future use of third-party
libraries, especially the C++17 STL's parallelization functions, these terms
are being updated to their Qt-specific collision-safe versions.

Discussion: https://octave.discourse.group/t/updating-qt-macro-names-to-avoid-name-collisions/5627
and discussions linked therein.

This patch makes the following changes through the part of the Octave codebase
using Qt:

* signals --> Q_SIGNALS
* slots --> Q_SLOTS
* emit --> Q_EMIT

The above changes were guided and verified by passing "-DQT_NO_KEYWORDS"
to CXXFLAGS when building Octave.

The .pro files in libgui were not used in the Octave build system and
were out of date.  Remove them to avoid confusion.

* libgui/gui.pro, libgui/qterminal/libqterminal/libqterminal.pro,
libgui/qterminal/qterminal.pro,
libgui/qterminal/qterminal/qterminal.pro: Delete obsolete files.

* TerminalView.cpp: (QRegion TerminalView::hotSpotRegion,
TerminalView::dropEvent): Replace foreach with range based for loop.
(TerminalView::paintEvent): If HAVE_QREGION_ITERATORS is not defined,
use Q_FOREACH instead of foreach.

* QWinTerminalImpl.cpp (QWinTerminalImpl::dropEvent):
Replace foreach with range based for loop.

* gui-utils.cc (adjust_to_screen):
Replace foreach with range based for loop.

* hist.m: Add check for the distance between max and min Y value when
calculating the bin locations.  If distance is less than 20*eps, use
calculation for distance = 0 to avoid error where X value separation is
smaller than eps and appear non-unique.  Add BISTs to check for no error
with small Y values with and without a specified number of bins.
* NEWS.9.md: Addd note about fix to hist.m line under Improvements and Fixes.

* graphics.cc (figure::reset_default_properties): Remove "innerposition", an
alias to "position", from the list of properties to reset.  Remove
"paperpositionmode" from list of properties to reset.
* graphics.cc (Freset): Update BIST test for figure objects to verify
"position" and "paperposition" are not reset.

* liboctave/util/glob-match.cc (symbol_match::match): GCC 14 warns about
potentially using an uninitialized variable when 'sym_wildc_idx' is incremented.
That is never an issue because it will always be initialized when that part of
the code is reached. Silence that compiler warning anyway by initializing it
with a dummy value early on.

inputParser.m: Call "builtin ('struct', ...)" rather than bare struct() to
avoid calling potentially overloaded 'struct' method.

* file-editor.cc (toplevel_changes): added missing call to original
  slot octave_doc_widget::toplevel_changed

* bug-53027.tst: Remove semicolons from "clear" statements not invoked as a
function.  Add semicolon to assert statements within %!test block.

* test/bug-53027/bug-53027.tst: Use unwind_protect blocks to ensure cleanup runs
also if tests failed.

* etc/NEWS.9.md: Update NEWS file with recent change for Octave 9.2.0.

* scripts/plot/appearance/legend.m (create_item): Take median color of patch or
surface objects for legend. Add demo with legend entry for patch object.

* tsearch.cc: Add programming note to doc about how to speed up runtime,
and update a block comment at the top.