Add scene-wide scene3Donly setting

1. Added `scene3DOnly` options to `Viewer`, `CesiumWidget`, and `Scene` constructors.
2. Removed `Primitive.allow3DOnly`
3. Added `FrameState.scene3DOnly` and make `Primitive` use it.
4. Made `Scene.mode` an ES5 property and have it throw when tryring to set a non-3D mode when scene3DOnly is true.
5. Made `DataSourceDisplay` take an options argument instead of individual parameters.
6. Update workaround in `DebugModelMatrixPrimitive` to avoid projected 0,0,0
7. Removed unused argument in StaticOutlineGeometryBatch
Fix typo.
Fix whitespace
Merge pull request #1901 from AnalyticalGraphicsInc/scene3d-only

Scene.scene3DOnly
Merge remote-tracking branch 'origin/master' into gltf-8