adds missing tests to doxygen documentation

python/yac.pyx

src/core/basic_grid.h

src/core/dist_grid.h

src/core/interp_method.h

src/core/io_utils.h

src/core/utils_common.h

src/mci/yac.h

src/mci/yac_module.F90

src/utils/read_icon_grid.h

src/utils/read_scrip_grid.h

tools/debug_grid2vtk.c

tools/weights2vtk.c