New databox class with brackets

Just trying a pull request with this, should be good for merging into master.  One test fails at the moment and that pointed me to _data_types.py line 646.  Does databox no longer have an attribute __name__?  I'm not sure exactly what insert_global is used for, but maybe take a look at this.

I'll close this branch and start a new branch with a meaningful name, such as test_making_branch.