Preference cleanup part 2

This brings the preferences in line with [the spreadsheet](https://docs.google.com/spreadsheets/d/1BkIjsHqTC3Yo6oXVcCiiCQaLcB5LzTEAS7UT5sDd9QU) apart from a couple of small changes which I will submit separately.

The upgrade path for the preferences requires this to be released as 2.2alpha66