REFLECTIONSNext to his solo debut, GARCIA, Jerry Garcia's REFLECTIONS is probably the strongest album the Grateful Dead's leading light made under his own name. It doesn't hurt that he's got the Dead backing him on half the tracks, but a band made up of both pals and studio vets stands up just as impressively on the rest. Aside from the cover tunes (including a transcendent take on Allen Toussaint's "I'll Take a Melody," where Garcia mixes magically with pianist