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/interaction/pointerinteraction.js

@@ -3,7 +3,6 @@ goog.provide('ol.interaction.Pointer');
 goog.require('ol');
 goog.require('ol.MapBrowserEvent.EventType');
 goog.require('ol.MapBrowserPointerEvent');
-goog.require('ol.Pixel');
 goog.require('ol.interaction.Interaction');
 goog.require('ol.object');