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/tileurlfunction.js

@@ -1,28 +1,10 @@
 goog.provide('ol.TileUrlFunction');
-goog.provide('ol.TileUrlFunctionType');
 
 goog.require('goog.asserts');
 goog.require('ol.math');
 goog.require('ol.tilecoord');
 
 
-/**
- * {@link ol.source.Tile} sources use a function of this type to get the url
- * that provides a tile for a given tile coordinate.
- *
- * This function takes an {@link ol.TileCoord} for the tile coordinate, a
- * `{number}` representing the pixel ratio and an {@link ol.proj.Projection} for
- * the projection  as arguments and returns a `{string}` representing the tile
- * URL, or undefined if no tile should be requested for the passed tile
- * coordinate.
- *
- * @typedef {function(ol.TileCoord, number,
- *           ol.proj.Projection): (string|undefined)}
- * @api
- */
-ol.TileUrlFunctionType;
-
-
 /**
  * @param {string} template Template.
  * @param {ol.tilegrid.TileGrid} tileGrid Tile grid.