Make StringOps a pure value class

This is the same treatment we gave ArrayOps previously. Some of the
more complex and nonsensical (for Strings) operations are provided for
compatibility. They delegate to WrappedString. Most operations have
efficient implementations in StringOps.

Author: szeiger

src/library/scala/collection/ArrayOps.scala

@@ -21,7 +21,7 @@ object ArrayOps {
       var i = 0
       while(i < len) {
         val x = xs(i)
-        if(p(x)) f(xs(i))
+        if(p(x)) f(x)
         i += 1
       }
     }
@@ -263,12 +263,12 @@ final class ArrayOps[A](val xs: Array[A]) extends AnyVal {
     * Note: `c splitAt n` is equivalent to `(c take n, c drop n)`.
     *
     *  @param n the position at which to split.
-    *  @return  a pair of arrayss consisting of the first `n`
+    *  @return  a pair of arrays consisting of the first `n`
     *           elements of this array, and the other elements.
     */
   def splitAt(n: Int): (Array[A], Array[A]) = (take(n), drop(n))
 
-  /** A pair of, first, all elements that satisfy prediacte `p` and, second, all elements that do not. */
+  /** A pair of, first, all elements that satisfy predicate `p` and, second, all elements that do not. */
   def partition(p: A => Boolean): (Array[A], Array[A]) = {
     var res1, res2 = ArrayBuilder.make[A]
     var i = 0