Get hit candidates from RTree, then refine result

Now we get exact hits also for lines and polygons.

src/ol/geom/linestring.js

@@ -146,3 +146,20 @@ ol.geom.LineString.prototype.getType = function() {
 ol.geom.LineString.prototype.getSharedId = function() {
   return this.sharedId_;
 };
+
+
+/**
+ * Calculate the distance from a coordinate to this linestring.
+ *
+ * @param {ol.Coordinate} coordinate Coordinate.
+ * @return {number} Distance from the coordinate to this linestring.
+ */
+ol.geom.LineString.prototype.distanceFromCoordinate = function(coordinate) {
+  var coordinates = this.getCoordinates();
+  var dist2 = Infinity;
+  for (var i = 0, j = 1, len = coordinates.length; j < len; i = j++) {
+    dist2 = Math.min(dist2, ol.geom.squaredDistanceToSegment(coordinate,
+        [coordinates[i], coordinates[j]]));
+  }
+  return Math.sqrt(dist2);
+};