UV Editor Improvements

Video captions: In VRED 2021.1, we have implemented a completely reworked UV Editor. First, we removed the Texture Editor, and all projection methods are available within the new editor, which makes working with textures more seamlessly. You can now also copy a UV layout from one object to another, which is a massive time saver when having identical objects in the scene. We also implemented the option to preserve the UVs when doing your retesselation of an object, so you don't need to create the UVs again. When creating a new UV layout, you can now enable Sew on Unfold, which simplifies the creation process. And we implemented and replaced the old unfold algorithm with a best-in-class Unfold3D library, which gives you much better results now and offers much more layout and optimize options. We also added a Select Shortest Path, which makes edge selection very easy now. Another new feature is the ability to constrain edges horizontally or vertically to make the UV layout fit to a rectangular texture. Just select the edges you want to constrain and apply the U or V constraint to it and unfold again. Now, you can apply your rectangular texture much better to your 3D models. Like here for the tire or for a seat belt, for example. For Show Texture, we added the option to choose between different channels of the material. If you're doing a selection in the UV Editor, you can now sync the 3D viewport, which makes orientation easier. You can also now export the UV layout as a snapshot with transparency, which is very helpful for the texture creation process. Find also many UV Editor settings in the preferences, like loading your own checkerboard texture or changing the color of your selections.