Merge competing Dataset approaches

[gerritholl]

Typhon currently has two competing Dataset approaches. One lives in the typhon.datasets package and its subpackages, another in typhon.spareice.datasets. The two have overlapping aims but diverge in their implementation and approach. This duplicates maintenance effort and in the long term, it is desirable to merge them. This requires a major effort.

To achieve this goal, it would be needed to make a full inventory of the features within each approach, where they overlap and where they differ. I suspect the typhon.datasets package has many features not currently available in typhon.spareice.datasets. It would affect readers implemented in either way.

Limitations of the typhon.datasets package:

• Limited documentation.
• Lacking tests.
• Overuse of multiple inheritance.
• Some methods defined in wrong place in class hierarchy.
• Hard to use. This is related to the limited documentation and the overuse of multiple inheritance, but that is not the only problem.

I don't expect to be able to do much on this any time soon, nor do I expect others to do so, but I'm keeping this issue here so we keep it in mind long term.