gwpy/gwpy: 0.12.0

Development release of GWpy. Backwards-incompatible changes: [#790] new gwpy.plot matplotlib interface, which replaces gwpy.plotter; the old interface is still there, but now carries a DeprecationWarning and will not be maintained [#845] gwpy.signal.filter has been removed as it was never well-maintained or documented [#868] new implementation of time-domain whitening with inverse-spectrum truncation Backwards-compatible changes: support for python3.7 [#872] new classmethod TimeSeriesDict.from_nds2_buffer [#878] new defaults for TimeSeries.spectrogram2 [#846] new overloaded Array.flatten and Array2D.T Bug-fixes (including package, unit test, and documentation updates): miscellaneous bug fixes miscellaneous documentation fixes a few updates to the examples See https://github.com/gwpy/gwpy/compare/v0.11.0...v0.12.0 for a full statement of what has changed since the last release