Parameter loading helper functions

We should add some helper functions that do things like read in parameters based on metadata, etc.

This would mainly be as debugging tools (easy way to load and inspect a parameter manually) but will probably be useful elsewhere too. They should probably let you stop at various points in the loading sequence (i.e. load the metadata, load the tar archive, load the dict with serialized values, load the dict with de-serialized values, load the whole parameter).