Camera jumps at the end of morphTo3D transition

[clkao]

To reproduce: https://cesiumjs.org/Cesium/Build/Apps/CesiumViewer/

1. click columbus view
2. drag the map to center somewhere in Africa
3. click 3d, observe the smooth transition but with the sudden jump back to US at the end

If it is to center back to US, the rotation should be part of the transition. But I think if the user interacted with the map (with 2), the current center should persist after the morph.

[nkbt]

Not only position is changed, but zoom level as well. Funny thing is that zoom level is not the same as zoom level on the first load.

Load Cesium sandbox - globe is about half of the screen, switch to 2d, switch back to 3d - globe is bigger then screen.

[mramato]

#3251 adds the ability to maintain camera position when morph duration is 0, but not yet when an animated morph occurs.