initial butterfly module

src/CMakeLists.txt

src/modules/butterflies/CMakeLists.txt

src/modules/butterflies/butterflies_dispersal.c

src/modules/butterflies/butterflies_dispersal.h

src/modules/butterflies/butterflies_main.c

src/modules/butterflies/butterflies_main.h

src/modules/butterflies/butterflies_populations.c

src/modules/butterflies/butterflies_populations.h

src/modules/butterflies/butterfly_actions.c

src/modules/butterflies/butterfly_actions.h

src/modules/butterflies/butterfly_vital_rates.c

src/modules/butterflies/butterfly_vital_rates.h

src/modules/butterflies/module.h

src/modules/butterflies/random_walk.c

src/modules/butterflies/random_walk.h