Update miniconda install
Merge pull request #1441 from rhattersley/update-miniconda

Update miniconda install
Handling for lbtim.ib=3 intervals
limit double cell method to mean climatologies
test changes
doc update
review action
Low-level read access to UM FieldsFile variants.
Merge pull request #1435 from rhattersley/ff-load

Low-level FieldsFile variant access
Merge pull request #1436 from esc24/lbtimbug

Handling for lbtim.ib=3 intervals
Support loading of LBC type fieldsfiles.
Review changes.