Where the imagination takes you when there are three days off between playoff games!   ---   Lindy Ruff watches the rain hit the window, studying the droplets as they join, organize themselves into tiny rivers and criss-cross paths on their journey down the glass.   These days, this is how he spends a lot of his time ? sitting and watching simple drops of water, seeing in their choreography something familiar from an earlier life.   He used to draw them, make them criss-cross, urge them