h4h5tools

H5toh4 tool still relies on using old hdp tool to verify that the conversion is correct. Some strange differences related to reference and vdata occurs. 
I change the testing script to use "hdiff" tool to compare instead. hdiff doesn't produce any differences between the expected output and the real output. 

Since this tool is not in a high priority to maintain, I just changed the testing shell script to use hdiff to compare instead.