* object.c:  Document NIL, TRUE, FALSE.
	* io.c:  Improve grammar in ARGF comment.  Document STDIN/OUT/ERR.
	  Document ARGF global constant.
	* lib/rake:  Hide deprecated toplevel constants from RDoc (import from
	  rake trunk).
	* lib/thwait.rb:  Document ThWait.
	* lib/mathn.rb:  Hide Math redefinition from RDoc
	* lib/sync.rb:  Add a basic comment for Sync_m, Synchronizer_m, Sync,
	  Synchronizer.
	* parse.y:  Document SCRIPT_LINES__.
	* hash.c:  Document ENV class and global constant.
	* vm.c:  Document TOPLEVEL_BINDING.
	* version.c:  Document RUBY_* constants.
	* ruby.c:  Document DATA and ARGV.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@32281 b2dd03c8-39d4-4d8f-98ff-823fe69b080e