Replace MCMC engine in PZMassfitter

[deapplegate]

Current MCMC engine in PZMassfitter is custom code by Adam Mantz. Would like to replace it with a standard MCMC library such as Emcee.

• Write new interface wrapper equivalent to pymc_mymcmc_wrapper.py to wrap pymc models for use by Emcee. (Does something already exist that does that?)
• Write new Runner classes for emcee that use new interface.

[anjavdl]

If you're referring to Adam's lmc package, that is public by now:
https://github.com/abmantz/lmc