adds max_search_distance option to NNN

doc/src/interp_methods.dox

examples/access_core/access_core.F90

examples/dynamic_config/dynamic_config.c

examples/interpolation_benchmark/toy_scrip.c

examples/toy_multi/toy_multi_common.c

examples/toy_output/toy_output.c

input/couple_config_test.yaml

python/src/examples/netcdf_writer.py

python/src/examples/plotter.py

python/yac.pyx

src/core/interp_method_nnn.c

src/core/interp_method_nnn.h

src/core/interp_stack_config.c

src/core/interp_stack_config.h

src/core/yac_core.F90

src/mci/config_yaml.c

src/mci/yac.c

src/mci/yac.h

src/mci/yac_global.F90

src/mci/yac_module.F90