Draft: Museum island basics

There have been plans with Example Suite creators to make a central teleporter hub that could be later expanded into something wider. This is what I've came up with. Most of the content is my original content, but textures, sounds and some models are other openly licensed content, such as CC-BY, CC0, osg license, I believe the Utah teaset uses gnu gpl, Stanford models have their own terms of use and so further. I also got a permit to use a low-poly version of the Benchy the Boat in this exhibition, but I haven't yet found time to set it up. I've tried to keep track of the relevant licensing information in all places, but it's worth another check.

The MR includes a basic island from cells [-1, -1] to [1, 1], a central building with the beginnings of an exhibition (example content). The theme of the teleporter hub is "3d game art museum" with plans that the exhibition of the museum could showcase OpenMW engine capabilities. This is the latest version of the museum island - a functional walking simulator with a bit of candy, but not much more. The exhibition will be developed further by me, and hopefully by others too. Most of the content uses Collada(.dae) format, but there are also .nif and .osgt examples.

This MR includes an incomplete version of OpenMWDude.dae, a file that's used to control the body part locations for the player model (and the NPC). There are plans to update the 3rd person model further.

I did test that this works, and did a clean up on this MR before submitting. It might still have some land textures that are unused, and possibly some meshes too.

The content requires the latest master (as of 22.1.2022) to work properly, as Collada features (especially alpha testing) isn't present in 0.47 release or earlier.