libcore: remove @rng from rand, and use traits instead.

Also, rename RandRes -> IsaacRng, and make the constructors static
methods.

Author: huonw

src/libcore/flate.rs

@@ -85,7 +85,7 @@ pub fn inflate_bytes(bytes: &const [u8]) -> ~[u8] {
 #[test]
 #[allow(non_implicitly_copyable_typarams)]
 fn test_flate_round_trip() {
-    let r = rand::Rng();
+    let r = rand::rng();
     let mut words = ~[];
     for 20.times {
         words.push(r.gen_bytes(r.gen_uint_range(1, 10)));

src/libcore/hashmap.rs

@@ -56,7 +56,7 @@ fn resize_at(capacity: uint) -> uint {
 pub fn linear_map_with_capacity<K:Eq + Hash,V>(
     initial_capacity: uint) -> HashMap<K, V> {
     let r = rand::task_rng();
-    linear_map_with_capacity_and_keys(r.gen_u64(), r.gen_u64(),
+    linear_map_with_capacity_and_keys((*r).gen_u64(), (*r).gen_u64(),
                                       initial_capacity)
 }
 

src/libcore/os.rs

@@ -1259,7 +1259,7 @@ mod tests {
     }
 
     fn make_rand_name() -> ~str {
-        let rng: @rand::Rng = rand::Rng();
+        let rng = rand::rng();
         let n = ~"TEST" + rng.gen_str(10u);
         assert!(getenv(n).is_none());
         n