Updated the master version.
Merge remote-tracking branch 'upstream/v1.5.x'
Merge remote branch 'upstream/v1.5.x'

* upstream/v1.5.x:
  Added example to iris.analysis.interpolate.linear docstring
  Bugfix to DimCoord.from_regular
  Change zorder of contour lines drawn by contourf.
  Modified cube dim_coords and aux_coords docstrings
  Simplified ionosphere example. Closes #603.
  Use space_weather.nc instead of missing file and enabled doctests
Added flexibilty when saving integer types to netCDF3
Ensure consistent memory layout for checksums.
Merge pull request #731 from rhattersley/normalise_checksum_data

Ensure consistent memory layout for checksums.
Refactor common code and fix for PEP8 1.4.6.
Merge pull request #5 from rhattersley/netcdf_int_fix

Refactor common code and fix for PEP8 1.4.6.
Merge pull request #745 from esc24/netcdf_int_fix

Added flexibilty when saving integer types to netCDF3
Switch to biggus for deferred loading
Update tests and results