[LyX/master] Get rid of Qt4 code in src/

[Jean-Marc Lasgouttes]

commit ac248e392dd6f97f0dbcfcd6ba4ffedde2daf774
Author: Jean-Marc Lasgouttes <lasgouttes at lyx.org>
Date:   Fri Nov 18 17:19:50 2022 +0100

    Get rid of Qt4 code in src/
    
    Qt4 code has been identidifed by
      git grep -l 'QT_VERSION.*\(0x050000\|0x04\)' src
    
    Uses of QT_VERSION_CHECK have been checked too.
    
    been used to remember what places need further work.
    
    Then remaining Qt4 references have been searched using
      git grep -i qt4
      git grep -i 'qt 4'
    and relevant issues have been either fixed or noted in the new
    TODO.killqt4 file.

 TODO.killqt4                        |   16 ++++++++
 src/frontends/qt/FancyLineEdit.cpp  |   17 ++-------
 src/frontends/qt/GuiApplication.cpp |   69 ++++-------------------------------
 src/frontends/qt/GuiApplication.h   |    9 -----
 src/frontends/qt/GuiBibtex.cpp      |    9 -----
 src/frontends/qt/GuiCitation.cpp    |    9 -----
 src/frontends/qt/GuiDocument.cpp    |   17 ++-------
 src/frontends/qt/GuiFontLoader.cpp  |   69 ++---------------------------------
 src/frontends/qt/GuiFontMetrics.cpp |   17 ++-------
 src/frontends/qt/GuiFontMetrics.h   |    2 +-
 src/frontends/qt/GuiImage.cpp       |   28 +--------------
 src/frontends/qt/GuiKeySymbol.cpp   |    4 +-
 src/frontends/qt/GuiLyXFiles.cpp    |    5 ---
 src/frontends/qt/GuiPainter.cpp     |    7 ----
 src/frontends/qt/GuiPrefs.cpp       |   16 +++------
 src/frontends/qt/GuiRef.cpp         |    5 ---
 src/frontends/qt/GuiSearch.cpp      |   34 ++----------------
 src/frontends/qt/GuiToolbar.cpp     |    2 +-
 src/frontends/qt/GuiView.cpp        |   27 +-------------
 src/frontends/qt/GuiWorkArea.cpp    |   31 +---------------
 src/frontends/qt/Menus.cpp          |   28 +++++---------
 src/frontends/qt/TocWidget.cpp      |    5 ---
 src/frontends/qt/qt_helpers.cpp     |   10 +----
 src/lyxfind.cpp                     |    9 +----
 src/support/FileMonitor.cpp         |    8 ----
 src/support/FileName.cpp            |    4 --
 src/support/Package.cpp             |   11 +-----
 src/support/filetools.cpp           |    6 +---
 28 files changed, 69 insertions(+), 405 deletions(-)