Bump version numbers to 1.4.2

CMake/options.cmake

CMakeLists.txt

FL/Enumerations.H

FL/Fl_File_Chooser.H

FL/Fl_Grid.H

FL/Fl_Help_Dialog.H

README.abi-version.txt

README.md

README.txt

configure.ac

documentation/src/index.dox

documentation/src/preface.dox

fltk-options/fltk-options.plist

fltk_version.dat

fluid/about_panel.cxx

fluid/about_panel.h

fluid/codeview_panel.cxx

fluid/codeview_panel.h

fluid/documentation/src/index.dox

fluid/fluid.plist