Write access to UM FieldsFile variants.
Placeholder update to .travis.yml
relaxed loading for bad PP headers
Test
Review changes
Fix sphinx comments
Switch to "enum" for file mode
Put temporary file in source directory
added field count improve warning msg
More review changes.
Final update to .travis.yml
Merge pull request #1443 from rhattersley/ff-save

Low-level write access to UM FieldsFile variants.
Merge pull request #1439 from pp-mo/lbc_levels

Support loading of LBC type fieldsfiles.
Merge pull request #1444 from esc24/bad_header

Relaxed loading for bad PP headers
Fix data loading problems.