* lib/rdoc.rb, lib/rdoc, test/rdoc: Update to RDoc 4.2.0.alpha(313287)

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47391 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* test/rdoc/test_rdoc_rdoc.rb (TestRDocRDoc#test_parse_file_encoding):
  typofix.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47392 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* remove trailing spaces.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47393 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* properties.

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