Account for null or undefined geometry

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.
Remove simple build profile

This was inadvertently added in d163f60e340423d46dc3b185da08d2de280be765 (see #2075).  Thanks @probins for the heads up.
Merge pull request #2108 from tschaub/simple

Remove simple build profile.
Merge pull request #2107 from tschaub/null-or-undef

Account for null or undefined geometry.
Dispatch change on feature id change
Provide a method for retrieving features by id
Disallow adding the same feature twice