fix texture-mesh rendering artifacts

src/mol-geo/geometry/texture-mesh/texture-mesh.ts

src/mol-gl/compute/marching-cubes/isosurface.ts

src/mol-gl/renderable/schema.ts

src/mol-gl/renderable/texture-mesh.ts

src/mol-gl/webgl/render-item.ts

src/mol-gl/webgl/uniform.ts

src/mol-math/geometry/gaussian-density/gpu.ts

src/mol-repr/structure/visual/gaussian-surface-mesh.ts

src/mol-repr/volume/isosurface.ts