Switch to biggus for deferred loading.
Update tests.
Remove obsolete import.
Update test
Revert test
Preserve old merge behaviour
Update test
Fix _create_field_data and tests
Fix tests for iris.fileformats.pp._interpret_fields
Fix indexing test result
Add support for fill_value
Allow single-cube data pass-through in merge.
Fix pickling
Fix interpolation test
PEP 8 fix to "Fix pickling"