Use "default" instead of None when creating distilled_hierarchies.
Also, miscellaneous corrections in messages and documentation. This solves issue #304 (provided this complies with the intention for the design of Cubes; that "default" hierarchy should be created if there is no hierarchy entry).
I made another commit which could fix the problem. i don't know how to merge the two commits, or make a new pull request which includes both changes.
Regarding your last comment, when you add a commit to a pull request branch the commit gets added to the pull request. That's ok.
I cannot reproduce #304 on current master.
I have tested this pull request and it causes several tests to fail. Seems there's other code referring to default dimensions as None.
An implicit hierarchy will always exist. I am unsure however whether a "default" hierarchy should be created or the extent of the impact of this patch.
I'd like to understand this better: what was the motivation to write this patch? I have no trouble accessing dimension or hierarchies without it.