Concluding recipe execution

[Peter9192]

There are some options:

1. The recipe only has datasets section
   In this case it downloads the data and applies specified/standard preprocessing (if it's not already available).
2. The recipe has datasets and experiments section
   In this case it should save comparison figures, and export the scores, and save each of the trained models
3. Recipe that loads new data and makes predictions with a saved model

[sverhoeven]

Data from datasets is saved to /tmp/output/save.csv
For example running src/springtime/recipes/model_comparison_usecase.yaml gives csv with header
year,geometry,breaking leaf buds_doy,tmin_1,tmin_2,tmin_3,tmin_4,tmin_5,tmin_6,tmin_7,tmin_8,tmin_9,tmin_10,tmin_11,tmin_12,tmax_1,tmax_2,tmax_3,tmax_4,tmax_5,tmax_6,tmax_7,tmax_8,tmax_9,tmax_10,tmax_11,tmax_12,Fpar_500m_1,Fpar_500m_2,Fpar_500m_3,Fpar_500m_4,Fpar_500m_5,Fpar_500m_6,Fpar_500m_7,Fpar_500m_8,Fpar_500m_9,Fpar_500m_10,Fpar_500m_11,Fpar_500m_12,Lai_500m_1,Lai_500m_2,Lai_500m_3,Lai_500m_4,Lai_500m_5,Lai_500m_6,Lai_500m_7,Lai_500m_8,Lai_500m_9,Lai_500m_10,Lai_500m_11,Lai_500m_12

[Peter9192]

After #192 springtime recipes no longer contain experiments.