Added a bit more content, early balancing attempts, still lots to do XD

I redid the gold and ruby sprites as they didn't feel quite right to the aesthetic I was aiming for. 

I also added in some new stone types as you get deeper as well as a partially redone player model with a simple moving animation.

Lots of work to do on performance as it definitely noticeably stutters as you move around and the world needs to load/unload. I think I hit the cap on what I can get out of the current voxel tutorial as it is more aimed at 3D, and doesn't cover my use cases as much, so I'll be improvising/searching for additional tutorials. 

I was originally aiming to have this be a fairly small in scope game, and while it technically is, having to learn voxels from scratch as part of it definitely added a lot of challenges and time to the process, but I think it will pay off in terms of a more fun overall game and also being able to take the knowledge and lessons learned to other future projects.