Get rid of stability annotations and document stability with api

This change adds a stability value to the api annotation, with
'experimental' as default value.

enum, typedef and event annotations are never exportable, but
api annotations are needed there to make them appear in the
docs.

Nested typedefs are no longer inlined recursively, because the
resulting tables get too wide with the current template.

src/ol/interaction/drawinteraction.js

@@ -29,13 +29,13 @@ ol.DrawEventType = {
   /**
    * Triggered upon feature draw start
    * @event ol.DrawEvent#drawstart
-   * @todo stability experimental
+   * @todo api
    */
   DRAWSTART: 'drawstart',
   /**
    * Triggered upon feature draw end
    * @event ol.DrawEvent#drawend
-   * @todo stability experimental
+   * @todo api
    */
   DRAWEND: 'drawend'
 };
@@ -56,7 +56,6 @@ ol.DrawEvent = function(type, feature) {
   /**
    * The feature being drawn.
    * @type {ol.Feature}
-   * @todo stability experimental
    */
   this.feature = feature;
 
@@ -71,7 +70,6 @@ goog.inherits(ol.DrawEvent, goog.events.Event);
  * @extends {ol.interaction.Pointer}
  * @fires {@link ol.DrawEvent} ol.DrawEvent
  * @param {olx.interaction.DrawOptions} options Options.
- * @todo stability experimental
  * @todo api
  */
 ol.interaction.Draw = function(options) {