features/FeatureLookupTable.js
function(feature) {
		if (!(feature in this.featureNameToFeatureIndex)) {
			var newIndex = this.featureIndexToFeatureName.length;
			this.featureIndexToFeatureName.push(feature);
			this.featureNameToFeatureIndex[feature] = newIndex;
		}
	}
function(feature) {
		if (!(feature in this.featureNameToFeatureIndex)) {
			var newIndex = this.featureIndexToFeatureName.length;
			this.featureIndexToFeatureName.push(feature);
			this.featureNameToFeatureIndex[feature] = newIndex;
		}
	}
add a single feature, if it does not exist