Fluid: last incremental chage, restructuring

fluid/CMakeLists.txt

fluid/app/Fd_Snap_Action.cxx

fluid/app/Fd_Snap_Action.h

fluid/app/Fluid_Image.cxx

fluid/app/Fluid_Image.h

fluid/app/fluid.cxx

fluid/app/fluid.h

fluid/app/mergeback.cxx

fluid/app/project.cxx

fluid/app/project.h

fluid/app/shell_command.cxx

fluid/app/shell_command.h

fluid/app/undo.cxx

fluid/io/Code_Writer.cxx

fluid/io/Code_Writer.h

fluid/io/Project_Reader.cxx

fluid/io/Project_Reader.h

fluid/io/Project_Writer.cxx

fluid/io/Project_Writer.h

fluid/nodes/Fl_Button_Type.cxx