New pp rule to calculate forecast period.
Modified plot.py to pass coords arg through to _map_common()
Review actions.
Revised grib load+save: extra levels translation, and grib <-> cf phenomenon translation from metadata project.
Merge pull request #482 from pp-mo/grib_translation

Revised grib load+save
Review actions.
Merge pull request #463 from esc24/plot_coords_keyword_fix

Plotting still uses map where possible even when 2D lat/lon are present.
Allows `coords` argument to select map coordinates when multiple options exist.
Fixes #448 and #468.
Review actions
Merge pull request #514 from esc24/pp_save_missing_fp

New pp rule to calculate forecast period.
Adds support for ieee 32bit fieldsfiles to iris.load
Added a ieee32 fieldsfile test.
BF - preserve masked arrays during aggregation
Merge pull request #527 from ajdawson/aggregate-missing

BF - preserve masked arrays during aggregation
Merge pull request #297 from pelson/ieee_32bit_fieldfile_support

Adds support for ieee 32bit fieldsfiles to iris.load
MAINT: update iris to use latest cartopy

Changes include fixing the transform points tests, experimental
regridding and the travis cartopy commit ref (v0.8.0).  iris pole
rotate and unrotate indexing has also been fixed to comply with
cartopy indexing of transform points.

Behaviour change includes plots now being limited by projection limits
rather than the data limits (where smaller than data limits).
Merge pull request #494 from cpelley/against_cartopy_master

updating iris to use cartopy v0.8.0
PEP8 fixes for aggregation tests
Merge pull request #531 from ajdawson/pep8-aggregation-tests

PEP8 fixes for aggregation tests
Added support for climatology bounds.
Added rules for transverse mercator grid.