BF: Only use the cross product (possibly negated) for the slice normal.

If the CSA slice normal is in the opposite direction then negate the
cross product. Fixes issue #137.
ENH: making the svd tol matching MATLAB's tol
BF: fixing RS.shape + use allclose (was allzeros)
BF+TST: Python 3 zero bytes error for offset

Nipy testing revealed that when the data offset is beyond the end of the
header we hit the unguarded use of '\x00' for a zero byte string, rather
than the needed ZEROB constant.
BF: make Bomber raise AttributeError instance

Bomber instance was causing problems for Python 3 inspect module because
it was raising an error for hasattr checks.  Make BomberError that is
instance of AttributeError to allow inspect to - er - inspect.
Merge pull request #140 from matthew-brett/py3-nipy-fixes

Py3 nipy fixes.

A couple of fixes to allow nibabel to work with Python 3 nipy.
DOC: Added some comments to clarify what is going on.
TST: Make sure the slice normal is sufficiently orthogonal, even when CSA slice normal is not.
TST: Additional tests for getting slice normal from DicomWrapper

Make sure the sign from the CSA slice norm is used.
Test assertion that CSA slice norm and cross product are parallel.
Merge pull request #138 from moloney/csa_slice_norm

BF: Only use the cross product (possibly negated) for the slice normal.

The information for the slice normal can come from the crossproduct of the within-slice axes, or the private Siemens CSA header.  These changes check that these are more or less the same apart from a sign flip, and then flips the cross-product vector if there is a sign flip in the CSA header slice normal.
TST: fix failing doctests on windows 64 bit

It seems that on windows 64 bit, Christophe Gohlke binaries, numpy
shape values come out as Long objects rather than python ints.
Merge pull request #142 from matthew-brett/win7-64-doctest-fixes

TST: fix failing doctests on windows 64 bit

It seems that on windows 64 bit, Christophe Gohlke binaries, numpy
shape values come out as Long objects rather than python ints.
DOC: update docstring to reflect new tolerance

Docstring incorrect in using S.shape rather than the shape of the
(matrix part of the) affine.
RF: simplify allclose test

alltrue redundant in allclose test
TST: add tests for io_orientations thresholding

Test the SVD and allclose thresholding for io_orientations
Merge branch 'io_orientation' into main-master

* io_orientation:
  TST: add tests for io_orientations thresholding
  RF: simplify allclose test
  DOC: update docstring to reflect new tolerance
  BF: fixing RS.shape + use allclose (was allzeros)
  ENH: making the svd tol matching MATLAB's tol
DOC: update mailmap for release
DOC: update Changelog for 1.3.0 release
DOC: update README / info.py

with note of Freesurfer compatibility.
DOC: update release instructions