don't use uninitialized row to determine whether it's a lat/lon row
make sure ot create space for a category before putting data into it
removed Category and Attribute classes
remove Indicator
IndicatorLite renamed ResultFeature
ResultFeature constructor moved to a static factory method
since 'category' and 'attribute' were both flattened into a single-level namespace, both terms have been generally discontinued and replaced by 'property', which is the term used in geojson