Linear pool method

[elray1]

Thanks, Emily! You're right, we need to check that and we don't right now. We will add it :)

[elray1]

Notes on how to do the validation Emily suggested:

• Separate function that does this check, called from validate_ensemble_inputs
• What this function validates:
  • Within each group defined by a combination of values for task id variables and output type, all models provided the same set of output type ids.
  • Check only applies to the cdf, pmf, and quantile output types. It is required for these types to ensure that the resulting distribution is valid (i.e., cdf values are increasing, pmf values sum to 1, and there is not quantile crossing). The check is not relevant to the mean, median, and sample types.