Simplify circularity test in nc load rules.
Define circularity from bounds, if any.
Added tests for old+new circular logic.
Fixed aggregate_by bug for single values coordinates.
Prevent a copy from having writable coordinate values on a DimCoord.
Updated the what's new. Better, but not complete.
Isolate pandas plotting side-effects.
Merge pull request #1210 from rhattersley/pandas-side-effect

Isolate pandas plotting side-effects.
What's new changes.
Merge pull request #20 from bjlittle/whats_new_actions

What's new changes.
Merge pull request #1212 from pelson/whats_new_review

Updated the what's new. Better, but not complete.
fixed bug when comparing string fill values
Merge pull request #1208 from pelson/aggregate_by_small

Fixed aggregate_by bug for single values coordinates.
Updated default mdtol for AreaWeighted.
Merge pull request #1214 from esc24/isnan_string_bug

fixed bug when comparing string fill values
Merge pull request #1215 from pelson/area_weighted

Updated default mdtol for AreaWeighted.
Extend test to cover bounds case.
Merge pull request #21 from bjlittle/coord_points_writable_extra

Extend test to cover bounds case.
Merge pull request #1209 from pelson/coord_points_writable

Prevent a copy from having writable coordinate values on a DimCoord.
Deprecated 'reset_load_rules'