Writes an HL_Node dataset to an HDF5 file.
Arguments:
rootGrp: The root group of the file.
parentNode: The parent node of the dataset to be written.
parentName: The name of the parent node.
childNode: The node to be written.
childName: The dataset's name.
doCompress: The compression level on the dataset, betwen 0-9 where 0 is no compression and 9 is highest compression.
Returns 1 upon success, otherwise 0.