Fix plain reading from file.
Fix plain reading from file.

It was broken too. Offset wasn't passed in number of double not
in bytes. Bug was masked by fact that we used chunks that was multiple
of 8, all values in file was same and that no one was looking at result

SKA-ScienceDataProcessor/RC,SKA-ScienceDataProcessor/RC,SKA-ScienceDataProcessor/RC,SKA-ScienceDataProcessor/RC,SKA-ScienceDataProcessor/RC