Bug fix release for the 2.3 series.

Most work on NiBabel so far has been by Matthew Brett (MB), Michael Hanke (MH)
Ben Cipollini (BC), Marc-Alexandre Côté (MC), Chris Markiewicz (CM), Stephan
Gerhard (SG), Eric Larson (EL), Yaroslav Halchenko (YOH) and Chris Cheng (CC).

References like "pr/298" refer to github pull request numbers.

2.3.2 (Wednesday 2 January 2019)

Enhancements

• Enable toggling crosshair with Ctrl-x in OrthoSlicer3D viewer (pr/701)
  (Miguel Estevan Moreno, reviewed by CM)

Bug fixes

• Read .PAR files corresponding to ADC maps (pr/685) (Gregory R. Lee, reviewed
  by CM)
• Increase maximum number of items read from Siemens CSA format (Igor Solovey,
  reviewed by CM, MB)
• Check boolean dtypes with numpy.issubdtype(..., np.bool_) (pr/707)
  (Jon Haitz Legarreta Gorroño, reviewed by CM)

Maintenance

• Fix small typos in parrec2nii help text (pr/682) (Thomas Roos, reviewed by
  MB)
• Remove deprecated calls to numpy.asscalar (pr/686) (CM, reviewed by
  Gregory R. Lee)
• Update QA directives to accommodate Flake8 3.6 (pr/695) (CM)
• Update DOI links to use https://doi.org (pr/703) (Katrin Leinweber,
  reviewed by CM)
• Remove deprecated calls to numpy.fromstring (pr/700) (Ariel Rokem,
  reviewed by CM, MB)
• Drop distutils support, require bz2file for Python 2.7 (pr/700)
  (CM, reviewed by MB)
• Replace mutable bytes hack, disabled in numpy pre-release, with
  bytearray/readinto strategy (pr/700) (Ariel Rokem, CM, reviewed by
  CM, MB)

API changes and deprecations

• Add Opener.readinto method to read file contents into pre-allocated buffers
  (pr/700) (Ariel Rokem, reviewed by CM, MB)