Changes for clojure.core/vec

Dmitry Kakurin on Mon, 30 May 2011
user=> (vec '(1 2 3))
[1 2 3]

user=> (vec [1 2 3])
[1 2 3]

user=> (vec '())
[]

user=> (vec nil)
[]
dpritchett on Tue, 13 Jul 2010
user=> (vec '(1 2 3))
[1 2 3]