Add example parameter files and a script generating right parameters

examples/SedovBlast_3D/run.sh

examples/SedovBlast_3D/sedov.yml

examples/create_ouput_fields.py

examples/main.c

examples/output_fields_examples/chemistry_eagle.yml

examples/output_fields_examples/chemistry_gear.yml

examples/output_fields_examples/chemistry_none.yml

examples/output_fields_examples/cooling_const_du.yml

examples/output_fields_examples/cooling_eagle.yml

examples/output_fields_examples/cooling_grackle.yml

examples/output_fields_examples/cooling_lambda.yml

examples/output_fields_examples/cooling_none.yml

examples/output_fields_examples/gravity_default.yml

examples/output_fields_examples/hydro_default.yml

examples/output_fields_examples/hydro_gadget2.yml

examples/output_fields_examples/hydro_gizmo.yml

examples/output_fields_examples/hydro_minimal.yml

examples/output_fields_examples/hydro_pressureentropy.yml

examples/output_fields_examples/hydro_shadowswift.yml

examples/output_fields_examples/stars_default.yml