dive sites, edit undo, and the major steps towards 4.9

[Dirk Hohndel]

> On Apr 13, 2019, at 2:06 PM, Salvador Cuñat <salvador.cunat at gmail.com> wrote:
> Forget the issue, it has gone after blowing away the build directory
> and making a clean build.
> Sorry for the noise.

Don't worry about it. While cmake has been MUCH better for me lately, I still have the occasional build failure that magically goes away if I blow away the build directory.

Magic.

/D