_tryFeature(x, y, dx, dy) {
        let featureName = RNG.getWeightedValue(this._features);
        let ctor = FEATURES[featureName];
        let feature = ctor.createRandomAt(x, y, dx, dy, this._options);
        if (!feature.isValid(this._isWallCallback, this._canBeDugCallback)) {
            //		console.log("not valid");
            //		feature.debug();
            return false;
        }
        feature.create(this._digCallback);
        //	feature.debug();
        if (feature instanceof Room) {
            this._rooms.push(feature);
        }
        if (feature instanceof Corridor) {
            feature.createPriorityWalls(this._priorityWallCallback);
            this._corridors.push(feature);
        }
        return true;
    }
Tries adding a feature
@returns {bool} was this a successful try?