Introduce "Modern CMake" in FLTK

This is a big commit and there are too many changes to list them all.
The main changes are:

- rename all CMake build options to 'FLTK_*'
- export library targets with namespace (prefix) 'fltk::'
- standardize shared library target names with suffix '-shared'
- set public build properties on libraries for consumers
- document library names and aliases in README.CMake.txt
- document changes in "Migrating Code from FLTK 1.3 to 1.4"
- partial backwards compatibility for old user projects

Included but not directly related changes:

- fix Windows (Visual Studio) DLL build
- add CMake function fl_debug_target() to show target properties
- don't build test programs if FLTK is a subproject
- internal: reformat CMake code: remove space before '('

Thanks to Matthias and Manolo for their help, testing, and feeback.

1 files changed, 2 insertions, 2 deletions

diff --git a/FL/Fl_Native_File_Chooser.H b/FL/Fl_Native_File_Chooser.H
index 721d0c1f4..92e21a98e 100644
--- a/FL/Fl_Native_File_Chooser.H
+++ b/FL/Fl_Native_File_Chooser.H
@@ -1,8 +1,8 @@
 //
 // FLTK native OS file chooser widget
 //
-// Copyright 1998-2016 by Bill Spitzak and others.
 // Copyright 2004 Greg Ercolano.
+// Copyright 2005-2024 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -108,7 +108,7 @@ class Fl_Native_File_Chooser_Driver;
  not turned off, the \p zenity -based dialog opens. This is expected to be more appropriate
  than other dialog forms for sandboxed apps.
  -# Else if the app runs under the KDE desktop and if command \p kdialog is available at run-time
- and if the library was not built with <tt>cmake -DOPTION_USE_KDIALOG=Off</tt>, the
+ and if the library was not built with <tt>cmake -D FLTK_USE_KDIALOG=OFF</tt>, the
  \p kdialog -based dialog opens.
  -# Else if the GTK library is available at run-time on the computer and if \p Fl::option(OPTION_FNFC_USES_GTK) is
  not turned off, the GTK-styled dialog opens. Call fl_register_images() to add  a "Preview" button to this dialog.