selection of cells
New features:
- new scheme for selecting cells in domain ; it now selects all cells that may intersect the domain ; this allows to use the same size for the computational domain and the data domain.
- new module for pure dusty gas (module_gas_composition_dust).
- renamed module_HI_model into module_HI_1216_model (for consistency).
- renamed module_D_model into module_D_1215_model (for consistency).
- some improvement of the verbose mode.