Merge pull request #14 from beckermr/master

support for multivariate Gaussian MH steps
Merge pull request #15 from beckermr/master

added checks to cov matrix to make sure it can be inverted and not fail
new configs
reworked model params

you now specify in the config file a dict for each model, keyed by model
name.  This contains currently the priors for each model.  See
config/pre001.yaml for an example.

Also refactored some code and prettyfied a bit.
Merge pull request #3 from esheldon/master

upstream sync