Pymatgen-db

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. New package maintainer, Dan Gunter <dkgunterlbl.gov>
. Added `vv.diff` package and associated `mgvv diff` subcommand, for taking the difference of two arbitrary MongoDB collections.
. Some cleanup and simplification of config files. `user` and `password` are accepted as aliases for `readonly_user` and `readonly_password`.

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1. MAPI_KEY is now a db config file variable.

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1. Minor bug fix release.

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1. Add option to use the Materials API to obtain stability data during run
insertion.
2. Materials Genomics UI now supports setting a limit on number of results
returned.
3. Improvements to mgdb script to allow setting of hosts, etc.

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1. Significant update to materials genomics ui. Ability to export table data
to CSV, XLS or PDF.
2. First vof RESTful interface implemented.