removed "Cancel" buttons from palette windows

Fltk/clippingWindow.cpp

Fltk/contextWindow.cpp

Fltk/fieldWindow.cpp

Fltk/fieldWindow.h

Fltk/manipWindow.cpp

Fltk/menuWindow.cpp

Fltk/messageWindow.cpp

Fltk/optionWindow.cpp

Fltk/partitionDialog.cpp

Fltk/pluginWindow.cpp

Fltk/pluginWindow.h

Fltk/projectionEditor.cpp

Fltk/solverWindow.cpp

Fltk/statisticsWindow.cpp

Fltk/visibilityWindow.cpp