doxygen: enable SOURCE_BROWSER
doxygen: enable SOURCE_BROWSER

Setting the SOURCE_BROWSER option to ON allows the file browser to list
all the source files, not only the headers.


Former-commit-id: 3dfbc3deee3843e4f18a9dc732fb06c4a55862e8
hdeling/sofa,Anatoscope/sofa,Anatoscope/sofa,hdeling/sofa,FabienPean/sofa,FabienPean/sofa,FabienPean/sofa,Anatoscope/sofa,hdeling/sofa,FabienPean/sofa,FabienPean/sofa,hdeling/sofa,FabienPean/sofa,Anatoscope/sofa,Anatoscope/sofa,Anatoscope/sofa,FabienPean/sofa,FabienPean/sofa,Anatoscope/sofa,hdeling/sofa,hdeling/sofa,FabienPean/sofa,Anatoscope/sofa,Anatoscope/sofa,hdeling/sofa,FabienPean/sofa,hdeling/sofa,hdeling/sofa,hdeling/sofa