Address doc comment rot in the standard library.

- Match @param/@tparam names to the actual parameter name
- Use @tparam for type parameters
- Whitespace is required between `*` and `@`
- Fix incorrect references to @define macros.
- Use of monospace `` and {{{}}} (much more needed)
- Remove `@param p1 ...` stubs, which appear in the generated docss.
  - But, retainsed `@param p1` stubs, assuming they will be filtered from
    the generated docs by SI-5795.
- Avoid use of the shorthand `@param   doc for the solitary param`
  (which works, but isn't recognized by the code inspection in IntelliJ
  I used to sweep through the problems)

The remaining warnings from `ant docs` seem spurious, I suspect they are
an unintended consequence of documenting extension methods.

  [scaladoc] /Users/jason/code/scala/src/library/scala/collection/TraversableOnce.scala:181: warning: Variable coll undefined in comment for method reduceOption in class Tuple2Zipped
  [scaladoc]   def reduceOption[A1 >: A](op: (A1, A1) => A1): Option[A1] = reduceLeftOption(op)
  [scaladoc]       ^

1 files changed, 1 insertions, 1 deletions

diff --git a/src/library/scala/collection/mutable/IndexedSeqLike.scala b/src/library/scala/collection/mutable/IndexedSeqLike.scala
index 4bd5ea1e89..2ff7ac8272 100644
--- a/src/library/scala/collection/mutable/IndexedSeqLike.scala
+++ b/src/library/scala/collection/mutable/IndexedSeqLike.scala
@@ -43,7 +43,7 @@ trait IndexedSeqLike[A, +Repr] extends scala.collection.IndexedSeqLike[A, Repr]
 
   /** Replaces element at given index with a new value.
    *
-   *  @param n       the index of the element to replace.
+   *  @param idx     the index of the element to replace.
    *  @param elem    the new value.
    *  @throws   IndexOutOfBoundsException if the index is not valid.
    */