Get hit candidates from RTree, then refine result

Now we get exact hits also for lines and polygons.

src/ol/coordinate.js

@@ -12,7 +12,8 @@ ol.CoordinateFormatType;
 
 
 /**
- * @typedef {Array.<number>}
+ * An array representing a coordinate.
+ * @typedef {Array.<number>} ol.Coordinate
  */
 ol.Coordinate;
 
@@ -84,6 +85,18 @@ ol.coordinate.scale = function(coordinate, s) {
 };
 
 
+/**
+ * @param {ol.Coordinate} coord1 First coordinate.
+ * @param {ol.Coordinate} coord2 Second coordinate.
+ * @return {number} Squared distance between coord1 and coord2.
+ */
+ol.coordinate.squaredDistance = function(coord1, coord2) {
+  var dx = coord1[0] - coord2[0];
+  var dy = coord1[1] - coord2[1];
+  return dx * dx + dy * dy;
+};
+
+
 /**
  * @param {ol.Coordinate|undefined} coordinate Coordinate.
  * @return {string} Hemisphere, degrees, minutes and seconds.