Included number of threads in main config; updated documentation.

    * iline: the line identifier for the line to be modeled, according to the molecule_{molname}.inp

    * width_kms: the range in km/s to be modeled around the line

    * nchannels: the number of channels to be considered

    * npix: the number of pixels in the final image

    * npix: the number of pixels in the final image; WARNING: it must be a multiple of the grid shape

    * threads: number of threads to be used by radmc

    * image_size_pc: the size of the image to produce; it is useful to get a good alignment

#### The global configuration file (`etl/config/config.yml`)

The global configuration file has only the "overrides" category:

The global configuration file has two categories, "computation" and "overrides":

* **computation:**

  * threads: number of threads to include in the multiprocessing pool

* **overrides:**

  dust_temperature_grid_type: the spacing in the dust temperature grid, can be: 'linear', 'log'

  dust_temperature_limits: the limits in the dust temperature grid, e.g. [10, 30]; the last point is excluded

  dust_temperature_step: the step size in the grid; if the spacing is logarithmic, it represents the increase factor,

  * dust_temperature_grid_type: the spacing in the dust temperature grid, can be: 'linear', 'log'

  * dust_temperature_limits: the limits in the dust temperature grid, e.g. [10, 30]; the last point is excluded

  * dust_temperature_step: the step size in the grid; if the spacing is logarithmic, it represents the increase factor,

  e.g. 10 means steps of one order of magnitude

  gas_density_grid_type: the spacing in the gas number density grid, can be: 'linear', 'log'

  gas_density_limits: the limits in the gas number density grid, e.g. [1e4, 1e8]; the last point is excluded

  gas_density_step: the step size in the grid; if the spacing is logarithmic, it represents the increase factor, e.g. 10

  * gas_density_grid_type: the spacing in the gas number density grid, can be: 'linear', 'log'

  * gas_density_limits: the limits in the gas number density grid, e.g. [1e4, 1e8]; the last point is excluded

  * gas_density_step: the step size in the grid; if the spacing is logarithmic, it represents the increase factor, e.g. 10

  means steps of one order of magnitude

  gas_density_unit: the units in which the gas number density is expressed, e.g. 'cm^-3'

  lines_to_process: the list of line identifiers to process, according to the molecule_{molname}.inp file,

  * gas_density_unit: the units in which the gas number density is expressed, e.g. 'cm^-3'

  * lines_to_process: the list of line identifiers to process, according to the molecule_{molname}.inp file,

  e.g. [['87', '86'], ['88', '87']]. The parameter is gives as a list of lists, so that the program knows which ratios

  to compute.

    dust_temperature_keyword = 'dust_temperature' if _model_type == 'isothermal' else 'dust_temperature_at_reference'

    parallel_args = product(dust_temperatures, densities, line_set, [density_keyword], [dust_temperature_keyword])

    with Pool(8) as pool:

    with Pool(config['computation']['threads']) as pool:

        results = pool.starmap(compute_grid, parallel_args)

    results_map = {}

    iline: 2

    width_kms: 10

    nchannels: 100

    npix: 200

    npix: 210

    threads: 12

    image_size_pc: 2