fixed MHSampler
Merge branch 'master' of https://github.com/piantado/LOTlib
Merge branch 'master' of https://github.com/piantado/LOTlib
merging with steve's changes
fixed weirdness in MHSampler step, and dual proposal
see MAJOR CHANGES
Merge branch 'master' of https://github.com/piantado/LOTlib

Conflicts:
	LOTlib/Grammar.py
testing updates
Added method for plotting GH posterior over MCMC samples (VectorSummary.lineplot_gh_metric); tested & works (w/ argument 'post').