Replace hardcoded mesh disposal with vertexArrayObjects iteration

See:
deathcap/voxel-mesher@dc0f31ff3d01e62bc30c8d46932a2b7ec9b8f805
deathcap/voxel-shader@aacf86064ad63a4f26545e1247fa7358ab61fad8
deathcap/voxel-wireframe@4d8744de249ce9a246f5518cc77ad6d1f7603b33
deathcap/voxel-chunkborder@19d53ad7e256db4507b5f4aa265595d9b365d28b