HDF5 Support

[aaronjridley]

Add support to read HDF5 files. This needs to:

• have flag for turning on during compilation
• have python code for turning (for example) SWMF runs into HDF5 files
• have a test for functionality

[aaronjridley]

The AMIE file readers should be written to also read in HDF5 files. This would simply be adding an HDF5 reader, but using exactly the same amie library routines to handle everything else.