etags harmonize names in Fields interface

Common/Gmsh.cpp

Common/OpenFile.cpp

Common/Options.cpp

Fltk/Main.cpp

Fltk/fieldWindow.cpp

Fltk/menuWindow.cpp

Geo/GModelIO_Geo.cpp

Geo/Geo.cpp

Mesh/Field.cpp

Mesh/Field.h

Parser/Gmsh.tab.cpp

Parser/Gmsh.y

Plugin/FieldView.cpp