Version 0.6.8 - mostly 3D model bug fixes

✔️event models now use instancing to improve performance. This can be disabled with instance:false
✔️Wait for model textures to load when loading map.
✔️fix models with multiple materials displaying with only one material
✔️fix models not displaying on events without a graphic
✔️imported models are now forced to use alpha cutoff unless supplied with alpha:true. This fixes a lot of common rendering problems.
✔️fix instanced models not working properly with alpha fog
✔️fix shadow(0) to match documented behavior (remove circular shadow while keeping dynamic shadow)
✔️fix base height clipping with depth tiles, and adjust depth tile behavior to be more consistent