There are times when everything in life seems just as clear as... mud. That’s doubly true if you happen to spend lots of time scrounging the Mississippi River, which is exactly what the characters in the latest from Jeff Nichols (director of 2011’s shamefully overlooked Take Shelter) do to get by. Centering on Ellis and Neckbone, two early-teens swamp rats who befriend a fugitive hiding out near their fishing spot,