This is a help function for GLMM_MCMC function.
THIS FUNCTION IS NOT TO BE CALLED BY ORDINARY USERS.
GLMM_MCMCprior.alpha(prior.alpha, lalpha)see argument prior.alpha of
GLMM_MCMC function
see output element lalpha of GLMM_MCMCdata
function
A list with the following components:
value of prior.alpha with added default values
where necessary
a numeric vector to be passed to C++