Make AverageAlgorithm require **any** inputs
Merged
requested to merge ghsc/users/erigler/geomag-algorithms:override_can_produce_data_AverageAlgorithm into master
Recent attempts to change the AverageAlgorithm to allow fewer than the full complement of inputs when calculating a mutli-station average were thwarted by the default can_produce_data() method in the parent Algorithm class, which required all inputs to be present, when what we now want is any inputs to be present.