ONELAB2: use onelabGroup from onelab2

CMakeLists.txt

Common/CommandLine.cpp

Common/Context.h

Common/Gmsh.cpp

Common/GmshMessage.cpp

Common/OpenFile.cpp

Common/Options.cpp

Common/onelab.h

Common/onelabUtils.cpp

Common/onelabUtils.h

Fltk/CMakeLists.txt

Fltk/FlGui.cpp

Fltk/gmshLocalNetworkClient.h

Fltk/graphicWindow.cpp

Fltk/graphicWindow.h

Fltk/onelab2Group.cpp

Fltk/onelab2Group.h

Fltk/onelabGroup.cpp

Fltk/viewButton.cpp

Geo/GeoStringInterface.cpp