Created Object interface for accessing object attributes.

This required a rename of the existing File.Name() to File.FileName().

Added some tests for h5f.
Refactored CreateGroup, simplified API
DataSet -> Dataset
DataSpace -> Dataspace
DataType -> Datatype
Refactored OpenGroup
Added File() method to Object interface. Refactored CreateDataset
Added tests for Dataset functionality
Abstracted OpenDataset
Update README.md
Use uint for Datatype sizes
h5pt: Fix Next, maybe.
Moved package to root
Update README
Minor cleanup of warnings and finalizer names.
Factor out OpenDataType code in to a common function.
DataType -> Datatype
Simplify init.
Clean up more things in hdf5.go
Error handling cleanup