Function to generate random initial values from a previous fit using adnuts
Source:R/utils.R
      sample_inits.RdFunction to generate random initial values from a previous fit using adnuts
Arguments
- fit
 An outputted list from
sample_admb- chains
 The number of chains for the subsequent run, which determines the number to return.
Value
A list of lists which can be passed back into
  sample_admb.