added method for pickling MCMCSummary
Added methods to VectorSummary.
Fixed some bugs, added some docs; VectorSummary.print_top_hypothesis still doesn't work.
Added pickle loading; pushing to run & pickle Summaries on Quine.
Did the last commit get everything?
Reorganized SimpleDemo a little bit.
Moved top hypotheses/samples methods from VectorSummary to MCMCSummary.
Added gridplot to VectorSummary -- when working this will allow us to see what happens with MCMC much easier.
Working more on gridplot.
Added MixtureGrammarHypothesis so we can do GrammarHypothesis inference with a mixture model (as in Josh's thesis).