'better' enable to 'get source' of instances of builtins such as tuples/sets;
extend _closuredsource to get free_vars in all cases (esp where not decorated)


git-svn-id: svn+ssh://svn.mystic.cacr.caltech.edu/pathos/dill@677 8bfda07e-5b16-0410-ab1d-fd04ec2748df
Merge branch 'master' of https://github.com/uqfoundation/dill