StringBuffer.java (toString): Don't mark buffer as shared.

	* java/lang/StringBuffer.java (toString): Don't mark buffer as
	shared.
	(insert(int,char[],int,int): New method.
	(delete): New method from Classpath.
	(deleteCharAt): Likewise.
	(substring): Likewise.
	(shared): No longer private.
	Added JavaDoc comments from Classpath.
	* java/lang/String.java (String(StringBuffer)): Ensure `buffer' is
	shared.

From-SVN: r33809