* lib/rexml/encoding.rb: use Ruby native encoding mechnism. [ruby-dev:42464]

* lib/rexml/encodings/: remove.

* lib/rexml/document.rb, lib/rexml/formatters/default.rb,
  lib/rexml/output.rb, lib/rexml/parseexception.rb,
  lib/rexml/parsers/baseparser.rb, lib/rexml/source.rb,
  lib/rexml/xmldecl.rb: use Ruby's native Encoding object.

* test/rexml/, test/rss/: follow the above encoding chagnes.

* NEWS: add REXML's incompatible change about encoding.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@29646 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/rexml/test_changing_encoding.rb

@@ -1,15 +1,13 @@
 #!/usr/bin/ruby -Ku
 # -*- coding: utf-8 -*-
 
-require 'kconv'
-require 'iconv'
 require 'rexml/encoding'
 
 
 class ChangingEncodings < Test::Unit::TestCase
   def initialize a
     @u = 'テスト ほげ ふが 美しい'
-    @e = Kconv.toeuc(@u)
+    @e = @u.encode("EUC-JP")
     @f = Foo.new
     super
   end