When you think of Ruth Westheimer, what immediately comes to mind is the image of a stout, wonderfully gregarious granny sporting a heavily accented potty mouth. But dig deeper, which documentarian Ryan White does in his informative, fascinating “Ask Dr. Ruth,” a fuller, much sadder portrait emerges; one of such misery, heartbreak and unmitigated tragedy it’s hard to believe she can even smile, let alone fill every room she enters with incandescent warmth and boundless [...]