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/source/wmtssource.js

@@ -29,7 +29,6 @@ ol.source.WMTSRequestEncoding = {
  * @constructor
  * @extends {ol.source.TileImage}
  * @param {olx.source.WMTSOptions} options WMTS options.
- * @todo stability experimental
  * @todo api
  */
 ol.source.WMTS = function(options) {
@@ -196,7 +195,6 @@ goog.inherits(ol.source.WMTS, ol.source.TileImage);
  * "dimensions" option, and possibly updated using the updateDimensions
  * method.
  * @return {Object} Dimensions.
- * @todo stability experimental
  * @todo api
  */
 ol.source.WMTS.prototype.getDimensions = function() {
@@ -228,7 +226,6 @@ ol.source.WMTS.prototype.resetCoordKeyPrefix_ = function() {
 /**
  * Update the dimensions.
  * @param {Object} dimensions Dimensions.
- * @todo stability experimental
  * @todo api
  */
 ol.source.WMTS.prototype.updateDimensions = function(dimensions) {
@@ -242,7 +239,6 @@ ol.source.WMTS.prototype.updateDimensions = function(dimensions) {
  * @param {Object} wmtsCap An object representing the capabilities document.
  * @param {string} layer The layer identifier.
  * @return {olx.source.WMTSOptions} WMTS source options object.
- * @todo stability experimental
  * @todo api
  */
 ol.source.WMTS.optionsFromCapabilities = function(wmtsCap, layer) {