Fixed (for good, I hope) normalisation bugs in ACL computation.
Slight changes to autocorr to bring in line with other similar estimators.
Added emcee_chain_autocorrelation_lengths to autocorr.py
Changed (yet again) acf estimator to use sum(|rho|) instead of sum(rho).
Added fburnin optional argument to emcee_chain_autocorrelation_lengths
Space and tickmarks back in plot_emcee_chains.
Added thin_emcee_chain to autocorr.py
Added thinned emcee chain function to autocorr module.
Removed duplication of chain thinning in autocorr.py; some cosmetic code changes.
Slight changes to autocorr formula.
Added basic emcee runner class to runner.py
Added thin_flatchain to runner.py.
Added run_to_neff to runner.py
More print statements in run_to_neff.
Even more diagnostic output in run_to_neff
Doc update for runner.py's save_state to match new pickled output.
Added load_runner function to runner.py
Changed runner's save_state command to only save a pickled runner instance.
Revert "Changed runner's save_state command to only save a pickled runner instance."

This reverts commit 02fa7d7c00931083a39f1c260a5b606eb2d6ba44.
Added logic in runner.py to deal with zero-length chain nicely in .thin_chain and .thin_flatchain