Changes for clojure.core/dec

zkim on Sat, 24 Jul 2010
user=> (dec 2)
1

user=> (dec 2.0)
1.0

user=> (dec 1)
0

user=> (dec -1)
-2
zkim on Sat, 24 Jul 2010
user=> (dec 2)
1

user=> (dec 2.0)
1.0

user=> (dec 1)
0

user=> (dec -1)
-2