Time to take all those DataExtension requests and sort them out

• Add an API for dynamic Extension data definition (preferably a builder)
• Refactor the DataExtension API implementation to use the builder with the annotation based API so that it is easier to understand.
• See if it is easy to add the group method data (eg giveData(Group forGroup))
• Implement a lot of new DataExtensions
• Implement suggestions for existing DataExtensions
• ..or close suggestions that turn out to be too much work