unit result auto path
Weights kwarg added to cube.collapsed, example plot updated to demonstrate its use
Replacement visual test image for edited gallery example
Cube.collapsed docstring edited so weights mentioned at start
Minor changes to docstring based on review suggestions
A further tidy of docstring for cube.collapsed
Merge pull request #774 from bblay/unit_res_path

unit result auto path
Merge pull request #882 from dkillick/weighted_collapse

Weights kwarg to cube.collapsed explicitly documented