New 'Corrprods' namespace for virtual sensors
New 'Corrprods' namespace for virtual sensors

Move all virtual sensors based on correlation products from the
'Antennas' namespace in SensorCache to their own 'Corrprods' namespace.
This should simplify pattern matching by using slashes to separate
groups (the preferred separator, it seems). Since everyone (?) accesses
(u,v,w) coordinates via the corresponding `DataSet` properties, no-one
should notice this.

ska-sa/katdal