Martin Short is not a national treasure — the Canadian comic actor and Hollywood superstar is a full-on continental treasure. Short is getting his flowers with new Netflix documentary Marty, Life is Short , directed by Lawrence Kasdan, the writer-director of The Big Chill , Wyatt Earp and Body Heat . Kasdan is incredibly accomplished, clearly — he’s been nominated for four Oscars — but it is also worth mentioning he’s the father of Jake Kasdan ( Walk Hard: The Dewey Cox Story and a bunch of TV work.) In addition to (Lawrence) Kasdan, Marty, Life is Short is produced by Sara Bernstein, Meredith Kaulfers, Christopher St. John, Justin Wilkes and Blair Foster. It is executive produced by Brian Grazer and Ron Howard through Imagine Documentaries, an arm of their Imagine Entertainment.…