tcltklib.c : add some methods to support multiple interpreters (low level)
MANUAL.euc : modify descriptions
tcltklib/sample/safeTk.rb : (new) sample : how to use safeTk interpreter
tk/sample/safe-tk.rb : (new) sample : how to use multi-tk.rb
tk.rb, tkafter.rb : bug fix and add feature to supprt multi-tk
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@4186 b2dd03c8-39d4-4d8f-98ff-823fe69b080e