The change in #2098 made it so a feature's geometry could be undefined. This is consistent with the return type for the getGeometry method. Where calling code needs to ensure that it has a geometry instance, it can use instanceof, goog.isDefAndNotNull(), or test for a truthy value.
This commit simplifies the exports.js plugin so it only relies
on the stability notes to generate the documentation, which
completely decouples it from the exportable API.
As a rule of thumb, whenever something has an 'api' annotation,
it should also have a 'stability' annotation. A more verbose
documentation of ol3 specific annotation usage is available in
the new 'apidoc/readme.md' file.
This commit also modifies all source files to implement these
usage suggestions.
