update to YAC 3.1.0

ChangeLog

NEWS

libcdi

src/grid_point_search.cc

src/lib/yac/Makefile.am

src/lib/yac/area.c

src/lib/yac/area.h

src/lib/yac/basic_grid.h

src/lib/yac/basic_grid_data.h

src/lib/yac/bnd_circle.c

src/lib/yac/check_overlap.c

src/lib/yac/clipping.c

src/lib/yac/clipping.h

src/lib/yac/compare_files

src/lib/yac/ensure_array_size.c

src/lib/yac/ensure_array_size.h

src/lib/yac/field_data.h

src/lib/yac/geometry.h

src/lib/yac/grid.h

src/lib/yac/grid_cell.c