naming conventions don't match R style guides

[AngusMcLure]

R style is to use all snake_case for functions and datasets etc. I should go and change all the names to every function and dataset to all lowercase and include CamelCase names as aliases

Also some of the function names feel a bit clunky and not R-like. R tends to prefer terse lowercase acronyms which I don't like, but might be worth considering some naming convention like:

pglm (pooled generalised linear model)
pglmm (pooled generalised linear mixed model)

pglmm_bayes (pooled generalised linear mixed model in a bayesian framework)

get_prevalence (getPrevalence)

pprev (PoolPrev)
hpprev (HeirPoolPrev)