Move top-level typedefs to typedefs.js

With one exception, those directly in the `ol` namespace can be moved without problem.
Some left-over goog.requires are also removed.

src/ol/featureloader.js

@@ -1,5 +1,3 @@
-goog.provide('ol.FeatureLoader');
-goog.provide('ol.FeatureUrlFunction');
 goog.provide('ol.featureloader');
 
 goog.require('goog.asserts');
@@ -11,38 +9,6 @@ goog.require('ol.proj.Projection');
 goog.require('ol.xml');
 
 
-/**
- * {@link ol.source.Vector} sources use a function of this type to load
- * features.
- *
- * This function takes an {@link ol.Extent} representing the area to be loaded,
- * a `{number}` representing the resolution (map units per pixel) and an
- * {@link ol.proj.Projection} for the projection  as arguments. `this` within
- * the function is bound to the {@link ol.source.Vector} it's called from.
- *
- * The function is responsible for loading the features and adding them to the
- * source.
- * @api
- * @typedef {function(this:ol.source.Vector, ol.Extent, number,
- *                    ol.proj.Projection)}
- */
-ol.FeatureLoader;
-
-
-/**
- * {@link ol.source.Vector} sources use a function of this type to get the url
- * to load features from.
- *
- * This function takes an {@link ol.Extent} representing the area to be loaded,
- * a `{number}` representing the resolution (map units per pixel) and an
- * {@link ol.proj.Projection} for the projection  as arguments and returns a
- * `{string}` representing the URL.
- * @api
- * @typedef {function(ol.Extent, number, ol.proj.Projection) : string}
- */
-ol.FeatureUrlFunction;
-
-
 /**
  * @param {string|ol.FeatureUrlFunction} url Feature URL service.
  * @param {ol.format.Feature} format Feature format.