Improve thread safety of beta sampler. 
Remove possible infinite loop from body of TruncNormal.
Add input check to TruncNorm sampler
add const keyword to variable in gamma sampler
add simple progress message.
Improve stability of hull inverseCdf. 
Previously, large negative numbers were resulting in taking the log of
zero.
Fix bugs in updateMu, updateGammaAndU.
Add chain diagnostic printer.
Add logspaceSubtract function
ignore update.
Add a shortcut test function