Pymatgen

* Type hints now available for core classes.
* New pymatgen.util.typing module for useful types.
* Misc bug fixes.

* New EntrySet class for easy manipulation of entries to grab subsets,
remove non-ground-states, etc. Makes it easier to grab a large set of entries and work with sub chemical systems. Also MSONable for caching.
* Performance improvements in core classes and Poscar (ExpHP).
* New/changed methods for IcohpCollection and Completecohp

* New Trajectory class for MD simulations (sivonxay)
* Lattice.get_vector_along_lattice_directions (blondgeek)
* Misc bug fixes.

* Python 3 only!
* Improvements to local environment code including VESTA bond emulation (utf)
* Update Cohp analysis (JaGEO)
* Updates to Boltztrap2 (fraricci)

* Pymatgen is now Py3 ONLY. If you need Py27 support, please use versions
< 2019.1.1.
* PARCHG parsing from WAVECAR (mturiansky)
* Improvements to defect generation algorithms (dbroberg)
* Simplifications to COHP plotting (JaGeo)

* Support for IUPAC ordering of elements in Composition formulae (utf)
* Various bug fixes including returning integer miller indices, catching negative values in Composition and fixes to graph analysis (utf), fix to Composition serialization (jmmshen), defect analysis (HanmeiTang), removing sites in surfaces (yiming-xu), and fix to support the new PROCAR format in VASP (dkorotin)
* `PMG_MAPI_ENDPOINT` environment variable added to support different endpoints for the Materials Project REST interface (mkhorton)