Improve performance of clojure.core/last

[Juan Facorro]

Compared to Clojure JVM, calling last on a range takes (at least) more than three times in Clojerl.

:clj	:clje	:runs	:time-clj	:time-clje	:ratio
[r (range 1000000)], (last r)	[r (range 1000000)], (last r)	1	68	218	3.21

(Number take from here)

There is not clear indication of why this is the case. clojure.lang.Range implements the IChunkedSeq interface but that is not being used in the implementation of last (see below).

(def 
 ^{:arglists '([coll])
   :doc "Return the last item in coll, in linear time"
   :added "1.0"
   :static true}
 last (fn ^:static last [s]
        (if (next s)
          (recur (next s))
          (first s))))

Even if last did use this interface clojerl.Range also implements the clojerl.IChunkedSeq protocol.