Proposed fix for issue 229 Location loader

[jandd661]

Issue: #229

Fixed issue with it not unloading the previous scene correctly/reliably. Added some TODOs for future expansion. Also provided some test scenes to load additively and update the Beach scene Scene Loader to load those scenes additively. Also provided the associated LocationSOs for those scenes.

Video: https://youtu.be/VQWs_yalU6o

[ciro-unity]

Hey @jandd661, a couple of things:

• As soon as I checkout your branch, I have 7 meta files which get created by Unity.
  
  I think it's because you haven't saved the assets in Unity before pushing, so the .meta files are not part of the PR. Always make sure to hit File > Save Project in the top menu before you commit for a PR.
• The LocationExit script in the Beach scene has a bunch of null references, which throws an error when testing it. Always make sure to test your solution as a very last thing before committing.
  
• I removed a couple of comments which were really superfluous.

But I'll merge now!