hdfview

Merge pull request #69 in HDFVIEW/hdfview from ~JHENDERSON/hdfview:feature/AttributeNatTable to hdfview-3

* commit '54d916310b55447c9cbe1a6319ea5cc34c83f44b':
  Remove an invalid TODO message
  Modify Attributes to align with Datasets
  Partial rework to support opening of Attributes in Compound TableView