Added h5datav3
Added h5datav3

Added original h5datav3.py file, based on h5datav3.py, but modifying the H5 file
locations for sensor information, so match those used in the new RTS ingest.

Outstanding issues:
- The script parameter sensors are not yet set by the simulator. They are just
  mocked up for the  moment.
- The calculated centre frequencies are also outstanding. This is also mocked
  up for the moment.

ska-sa/katdal