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, 1 insertions, 1 deletions

diff --git a/FL/Fl_Printer.H b/FL/Fl_Printer.H
index 4a3f9177b..7da0f1da5 100644
--- a/FL/Fl_Printer.H
+++ b/FL/Fl_Printer.H
@@ -75,7 +75,7 @@
  <li>If the GTK library is available at run-time, class Fl_Printer runs GTK's printer dialog which allows to set
  printer, paper size and orientation.
  <li>Under the KDE desktop, Fl_Printer runs the <tt>kdialog</tt> command to create KDE-styled file dialogs if
- that command is available at run-time, unless FLTK was built with CMake and option OPTION_USE_KDIALOG turned off.
+ that command is available at run-time, unless FLTK was built with CMake and option FLTK_USE_KDIALOG turned off.
  In that case, Fl_Printer attempts to run the GTK dialog.
  <li>If the GTK library is not available, or if Fl::option(Fl::OPTION_PRINTER_USES_GTK) has been turned off,
  class Fl_Printer runs FLTK's print dialog.