wip, per-object transparency

src/mol-geo/geometry/direct-volume/direct-volume.ts

src/mol-geo/geometry/lines/lines.ts

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

src/mol-geo/geometry/points/points.ts

src/mol-geo/geometry/spheres/spheres.ts

src/mol-geo/geometry/text/text.ts

src/mol-geo/geometry/transparency-data.ts

src/mol-gl/_spec/renderer.spec.ts

src/mol-gl/renderable/direct-volume.ts

src/mol-gl/renderable/schema.ts

src/mol-gl/shader/chunks/apply-marker-color.glsl

src/mol-gl/shader/chunks/assign-color-varying.glsl

src/mol-gl/shader/chunks/assign-material-color.glsl

src/mol-gl/shader/chunks/color-frag-params.glsl

src/mol-gl/shader/chunks/color-vert-params.glsl

src/mol-repr/representation.ts

src/mol-repr/shape/representation.ts

src/mol-repr/structure/complex-visual.ts

src/mol-repr/structure/units-visual.ts

src/mol-repr/visual.ts