Monkey patch iris

[znicholls]

Pull request

Please confirm that this pull request has done the following:

• Tests added
• Documentation added (where applicable) (N/A)
• Example added (either to an existing notebook or as a new notebook, where applicable) (N/A)
• Description in CHANGELOG.rst added

Adding to CHANGELOG.rst

Please add a single line in the changelog notes similar to one of the following:

- (`#XX <http://link-to-pr.com>`_) Added feature which does something
- (`#XX <http://link-to-pr.com>`_) Fixed bug identified in (`#XX <http://link-to-issue.com>`_)

[znicholls]

@lewisjared can you take a look. It seems ok except there must be some weird race condition as the scratch script is producing the following error (full log in email)

$ bash scripts/scratch-process.sh 
...
2019-07-10 10:44:59,394 ERROR:netcdf_scm.iris_cube_wrappers:Missing CF-netCDF measure variable 'areacella', referenced by netCDF variable 'sftlf'. Tried to add areacella cube but another exception was raised:
Traceback (most recent call last):
  File "...netcdf-scm/src/netcdf_scm/masks/__init__.py", line 387, in get_mask
    return self._masks[mask_name]
KeyError: 'World|Land'

ValueError: Duplicate cell_measures are not permitted.

[codecov]

Codecov Report

Merging #68 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #68      +/-   ##
==========================================
+ Coverage   97.94%   97.96%   +0.01%     
==========================================
  Files          10       10              
  Lines        1168     1179      +11     
  Branches      163      165       +2     
==========================================
+ Hits         1144     1155      +11     
  Misses         16       16              
  Partials        8        8

Impacted Files	Coverage Δ
src/netcdf_scm/utils.py	97.1% <ø> (ø)	⬆️
src/netcdf_scm/masks/__init__.py	100% <100%> (ø)	⬆️
src/netcdf_scm/iris_cube_wrappers.py	99.17% <100%> (+0.01%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6c3f922...288c16d. Read the comment docs.

[rgieseke]

LGTM

[znicholls]

Closing in favour of #72