moved corana, griewangk, and zimmermann to storn to fix pickling of models;
fixed import of corana in examples


git-svn-id: svn+ssh://svn.mystic.cacr.caltech.edu/mystic/mystic@766 968178ea-60bd-409e-af13-df8a517b6005
convert tuple of degenerate solved values to dict format in _solve_single


git-svn-id: svn+ssh://svn.mystic.cacr.caltech.edu/mystic/mystic@767 968178ea-60bd-409e-af13-df8a517b6005
fix: impose_product should also work when prod is negative


git-svn-id: svn+ssh://svn.mystic.cacr.caltech.edu/mystic/mystic@768 968178ea-60bd-409e-af13-df8a517b6005
Merge branch 'master' of https://github.com/uqfoundation/mystic