openlayers 6.x-2.0-alpha3

This is mainly a bugfix release, as well as a point of stability before future releases which may change the names of vital hooks [1].

Among the many bugs fixed since 2.0-alpha2, the most important are related to the completion of CCK functionality (with the exception of [2]. This release also includes fixes for the KML layer type, the ZoomToLayer functionality, editing and reverting layers, and it adds to the documentation and tests in the 2.x branch. It is a recommended update for all users of 2.x who are using tagged releases.

[1]: #723530: Change name of Style and Layer hooks
[2]: #721924: CCK does not limit features