pyfive version 0.3.0

Some highlights from the release:

• support for dimension scales via the Dataset.dims attribute
• reading from BytesIO objects
• File can be used as a context manager
• references
• Support for a number of new attribute types:
  • complex64
  • complex128
  • variable length sequences
  • arrays
  • references
• Dataset.fillvalue attribute
• fletcher32 checksums