SciTools/iris — pull request #273 by pp-mo (2012-12-11 14:59:50+00:00)
Title: control cube iteration

Addresses #86
cf. Jira SCIT-25

For now:
* mechanism to switch support between allow/disallow/deprecate.
* default is now 'deprecate', which gives a warning
* tests for all-options, and allow-only (which then fails if setting is 'disallow')

Future Intentions:
* when ready to disallow, remove switch + leave disabling code only.