minor mcmc modes

mcmc mods
Merge branch 'master' of https://github.com/jolyonb/deevolve

Conflicts:
	mcmcdev/chains/chain_10000.dat
	mcmcdev/chains/chain_10001.dat
	mcmcdev/mcmc
	mcmcdev/src/main.cpp
	mcmcdev/src/main.h