Ruby

• math.c: Attach documentation for Math.
  * 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