has3dData element is not set correctly

[jones139]

The has3dData element in events is set if the datapoints contain a 'data3d' element, irrespective of if the size of the 3d array is zero or if it contains all zeroes - has3dData should only be set if there is valid 3d data for the event.

[jones139]

This should be quite an easy fix in the tidy_db function - we then need to re-process the database and create a new release of the database.