ENH: Added funtions to transform orientations.

Also added funtion to get orientations from axes codes.
DOC: Fixed typo in axcodes2ornt docstring
BF: ornt_transform was returning the inverse of the correct orientation.

Also fixed string formatting bug when an invalid orientation is passed in.
Merge pull request #146 from moloney/enh-orientations

ENH: Added funtions to transform orientations.

Work out orientation affine / coding to map from one voxel coding to another.

Calculate orientation coding corresponding to given axis codes.
BF: doctest output not correctly formatted

Doctest result for `axcodes2ornt` was correct in content, but not
identical to the doctest output.
enh: allow for additional keyword arguments to be passed to pydicom
NF: context to run command in given directory

Useful when you want to use ``InTemporaryDirectory`` but you are still
debugging; do a temporary replacement with ``InGivenDirectory`` and pass
a known directory for the test, and look at the products there, before
swapping back to ``InTemporaryDirectory`` when the tests are fixed.
RF: don't use setuptools for bdist_wininst

Setuptools not necessary; the command is in distutils.
fix: changed to specific keyword arg and added test
py3: compatibility fix
Merge pull request #147 from satra/fix/mosaicreader

ENH: allow for additional keyword arguments to be passed to pydicom
BF: fix for dtype printing doctest failure

Fix by doing an ellipsis for the dtype location
TST+DOC: docstrings and tests for InGivenDirectory

Funnily enough, InGivenDirectory was deleting the contents of the Given
directory, which is a bit error prone.  Don't do that, and add test
module to test behavior.
BF: use realpath to make directory name canonical

Getting travis build errors that might be to do with symbolic links
Merge pull request #153 from matthew-brett/affine-doctest-fix

BF: fix for dtype printing doctest failure



Fix by doing an ellipsis for the dtype location

Fixes issue gh-151
Merge pull request #148 from matthew-brett/temp-dir-debugging

NF: context to run command in given directory

Useful when you want to use InTemporaryDirectory but you are still
debugging; do a temporary replacement with InGivenDirectory and pass
a known directory for the test, and look at the products there, before
swapping back to InTemporaryDirectory when the tests are fixed.