Changed *point-pred* From A Function To An Expression
Changed *point-pred* From A Function To An Expression

Now that *point-pred* is a racket expression, it's both a lot easier to
debug it, and simpler to append things to it. Might come with a bit
extra overhead, but not much.

jackfirth/herbie,jackfirth/herbie,jackfirth/herbie,jackfirth/herbie,jackfirth/herbie,jackfirth/herbie