reduce number of webgl state changes

CHANGELOG.md

src/mol-canvas3d/passes/draw.ts

src/mol-canvas3d/passes/fxaa.ts

src/mol-canvas3d/passes/marking.ts

src/mol-canvas3d/passes/multi-sample.ts

src/mol-canvas3d/passes/postprocessing.ts

src/mol-canvas3d/passes/smaa.ts

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

src/mol-gl/compute/grid3d.ts

src/mol-gl/compute/histogram-pyramid/reduction.ts

src/mol-gl/compute/histogram-pyramid/sum.ts

src/mol-gl/compute/marching-cubes/active-voxels.ts

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

src/mol-gl/compute/util.ts

src/mol-gl/renderer.ts

src/mol-gl/scene.ts

src/mol-gl/webgl/context.ts

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

src/mol-gl/webgl/state.ts

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