stream surface --> stream ribbon, fix description of twoswirls

refine cases in chatvis_bench, and object identification cases

modify vision rubrics in main cases, add overall visualization goals to every cases, and remove rubrics that cannot be rated by comparing GT and result images

rubric edits from Jason Sun

add 6 stream surface, pathline, path surface, streakline, timeline cases from Kaiyuan Tang

add 16 vector field cases from Kaiyuan Tang

add two molecular vis workflow cases from Helgi Ingolfsson