gam0_natural_params: Transform gamma HMM parameters from working to natural
In simonecollier/lizardHMM: Fitting Lizard Movement Data with HMMs

This function transforms the working gamma HMM parameters back into the original format of the natural parameters and outputs them as a list. This function is the reverse of norm_working_params().

gam0_natural_params(
  num_states,
  num_variables,
  num_subjects,
  num_covariates,
  working_params,
  state_dep_dist_pooled = FALSE
)

`num_states`	The number of states in the desired HMM.
`num_variables`	The number of variables in the data.
`num_subjects`	The number of subjects/trials that generated the data.
`num_covariates`	The number of covariates in the data that the transition probability matrix depends on.
`working_params`	A vector of the working gamma parameters for the HMM as outputted by `norm_working_params()`.
`state_dep_dist_pooled`	A logical variable indicating whether the state dependent distribution parameters `alpha` and `theta` should be treated as equal for all subjects.