Construct Animate r489

Notes

We've started doing a lot of internal work to prepare the engine for 3D rotations of more kinds of objects, including 3D shape (a long-standing request). We're working carefully but in case we missed something, please be on the lookout for anything amiss and be sure to file an issue if anything has gone wrong!

The 3D model object now has a new Transform mode property which you can now set to stretch to stretch the model to fill its box. This is useful for scenery or decorative models and works well with the new gizmo scale mode. The old way of fitting the model inside its box proportionally is called fit. However while implementing better support for 3D rotation, we realized that the old way of handling rotation in this mode wasn't quite right. To preserve backwards compatibility, the old mode is called Legacy and should work identically to how it did before; the new mode Fit is the default for newly added models, and better handles rotation.

Other improvements include some updates for the 3D editor, including refreshing the appearance of the top toolbar, refining how the gizmo works, and some other bug fixes. Happy testing!