Fix Camera.pickEllipsoid during morph

Calling `Camera.pickEllipsoid` during a morph would cause the result parameter to be returned, when in reality the result is `undefined` (which is what we already return when a pick is not on the ellipsoid).  I suppose ideally we would actually support pick ellipsoid during a morph, but that's hardly a feature I ever see being useful.

I added a test, but this is also easily testable with the Sandacastle picking example by showing coordinates under a mouse and then morphing.
Better mouse handling around the camera's constrained axis.
Fix tests.
Merge pull request #1854 from AnalyticalGraphicsInc/morph-pickEllipsoid

Fix Camera.pickEllipsoid during morph
Merge pull request #1858 from AnalyticalGraphicsInc/constrainedAxis

Camera Constrained Axis
Reorder b30 in CHANGES.md
More b30 reordering in CHANGES.md
Merge branch 'master' into camera-terrain

Conflicts:
	CHANGES.md
	Source/Scene/ScreenSpaceCameraController.js
	Specs/Scene/ScreenSpaceCameraControllerSpec.js