add support for writing out global coupling configuration

Makefile.am

doc/src/reference.dox

doc/src/usage.dox

doc/src/yaml_file.dox

input/coupling_test3_default.yaml

input/coupling_test3_default_c.yaml

src/mci/config_yaml.c

src/mci/couple_config.c

src/mci/couple_config.h

src/mci/yac.c

src/mci/yac.h

src/mci/yac_global.F90

src/mci/yac_module.F90

tests/mci/test_couple_config.c

tests/mci/test_dummy_coupling3.inc

tests/mci/test_dummy_coupling3_c.c

tests/mci/test_dynamic_config.F90

tests/mci/test_dynamic_config_c.c