Scroll wheel zoom goes through the earth

[hpinkos]

Reported on the forum: https://groups.google.com/forum/#!topic/cesium-dev/xeRAg8lObUg

If you go to this sandcastle:
http://cesiumjs.org/Cesium/Apps/Sandcastle/index.html?src=Geometry%20and%20Appearances.html&label=Showcases

Make the camera perpendicular to the earth then zoom in quickly as far/fast as you can using the mouse wheel with the mouse over a 3D shape, you'll zoom through the earth about 10-20% of the time.

NOTE: It doesn't seem to happen nearly as often if the camera is on an angle, or if the mouse isn't over a shape.

It only seems to happen for me on Mac OS X and Ubuntu. It does not happen on Windows. I am able to reliably re-create the issue using OS X Sierra and Chrome 55

[smills2929]

Not sure if it's related, but I've noticed that the viewer.scene.screenSpaceCameraController.minimumZoomDistance keeps being set to 0, regardless of what I set it to.

From a quick search of the Cesium source it seems that controller.minimumZoomDistance is being set in multiple places around the application every frame. How can I stop this being set to 0?

[pjcozzi]

CC #2968 and #3037

[hpinkos]

Closing as duplicate of #4855