new CubeList method to extract over common coord values
Changed to generator comprehension
Forecast/observation reference time
Use exact 'missing' values for grib loading.
Review changes.
new uk chem translations
Merge pull request #1366 from marqh/ukchem

New UK chem translations
grib2 trans
Review actions
Merge pull request #1364 from pp-mo/grib_mdi

Use exact 'missing' values for grib loading.
Tweak wording for encoding/MDI issues.
Merge pull request #1353 from bjlittle/reference-time

Forecast/observation reference time
Split tests and reduce size where appropriate.
Merge pull request #1367 from marqh/ggust

grib2 trans
Merge pull request #1368 from rhattersley/grib-mdi-wording

Tweak wording for encoding/MDI issues.
Merge pull request #1369 from rhattersley/quick-izip-tests

Split tests and reduce size where appropriate.
Helper for multiple mock patches.
Support for grib pdt 8.
Review changes.
Use assertRaisesRegexp in error message testing.