start rewriting mesh code in zig

todo.md

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+# current tasks
+yoink implementation of mesh into meshes.zig so i could modify it to add ambient occlusion vars
+implement ambient occlusion either
+ - via passing extra info to shader (can use 132 bits to indicate what tiles around the quad are obsuring light. need to pass as an extra variable)
+implement animated textures by either 
+ - making literally everything animated 
+ - somehow passing extra info to shader
+limit vertical camera rotations
+update libraries like raylib
+
+# future tasks
+implement chunk meshing cache to reduce delay on block placement 
+investigate binary/SIMD meshing for performance