Cleaned up Grammar. Moved real value parts of Grammar into sandbox.RealValueGrammar
Changed MetropolisHastings to be a class, for easier tracking of stats and subclassing. mh_sample should be replace dwith MHSampler, but there will be a hacked workaround for now
changed many inference techniques to be object-oriented (=savable and resumable and managable)
fixed errors in ParallelTempering
Merge branch 'master' of https://github.com/piantado/LOTlib

Conflicts:
	LOTlib/FunctionNode.py
	LOTlib/Grammar.py
	LOTlib/Hypotheses/Hypothesis.py