**ADDITIONS**
* New graphical user interface illustrating single-qubit functionality of scqubits.
* Introducing `NamedSlotsNdarray` as a convenient subclass of ndarray with name-based and value-based slicing, and immediate support for basic plots
* Added functionality for extracting dispersive energy parameters (such as Kerr coupling strengths)
* Improved support for transition plots (subsystem transitions, sidebands etc.)
* Added `Cos2PhiQubit` class.
* Added `KerrOscillator` class
* Added `GenericQubit` (two-level system) so that toy models such as the Jaynes-Cummings model can be readily realized with `HilbertSpace`.
* Added `n` and `phi` operators to the Oscillator class
* Added helper methods `convert_to_E_osc` and `convert_to_l_osc` for `Oscillator` initialization
* New and enhanced interface for defining interaction terms in HilbertSpace objects via .add_interaction()
* Added option to input interaction as a Qobj, or specify interaction terms as string expressions; also represented in HilbertSpace GUI
**IMPROVEMENTS**
* Convergence for `ZeroPi` is now faster, thanks to a correction to the expression for the grid spacing in discretization.py.
* Refactored `ParameterSweep` class, now allowing for multi-dimensional parameter sweeps
* Added a warning describing total=True being the default in t1 calculations
**BUG FIXES**
* Fix to type conversion error affecting the `number` operator in operators.py
* Rectified orientation of `matrix2d` plots to match axes labels
* Use of `mode` in values displayed in matrix element plots
**INTERNALS**
* New support for higher-order stencils in discretized derivatives.
* Improved formatting of `__str__` methods (called when "printing" an scqubits class instance).
* Under the hood: use of Python 3.6 compatible type annotations; unified formatting enabled by the `black` package
* Improvements to fileIO speeding up operations (increased memory cache) and requiring less disk space (avoid literal redundancies in stored data).