Naive cgo bindings for the C-API of hdf5.

http://godoc.org/github.com/sbinet/go-hdf5

• Hello world example: https://github.com/sbinet/go-hdf5/blob/master/cmd/test-go-hdf5/main.go

• Writing/reading an hdf5 with compound data: https://github.com/sbinet/go-hdf5/blob/master/cmd/test-go-cpxcmpd/main.go

• Only version 1.8.x of HDF5 is supported.
• In order to use HDF5 functions in more than one goroutine simultaneously, you must build the HDF5 library with threading support. Many binary distributions (RHEL/centos/Fedora packages, etc.) do not have this enabled. Therefore, you must build HDF5 yourself on these systems.

• the h5pt packet table interface is broken.
• support for structs with slices and strings as fields is broken