avoid SEGV trouble.
  [KNOWN BUG] When supports pthread and running multiple Tk interpreters,
  an interrupt signal causes SEGV frequently. That may be a trouble of
  Ruby's signal handler.
* ext/tk/tkutil/tkutil.c; fix a bug on converting a SJIS string array
  to a Tcl's list string.
* ext/tk/tcltklib.c: wrap Tcl's original "namespace" command to
  protect from namespace crash.
* ext/tk/lib/multi-tk.rb: enforce exception-handling.
* ext/tk/lib/multi-tk.rb: catch IRB_EXIT to work on irb.
* ext/tk/lib/tk.rb: ditto.
* ext/tk/tcltklib.c: add TclTkLib.mainloop_thread?
* ext/tk/lib/multi-tk.rb: (bug fix) callback returns a value.
* ext/tk/lib/tk/canvas.rb (delete): bug fix when multiple arguments.
* ext/tk/lib/clock.rb: fix 'no method error'.
* ext/tk/lib/clock.rb (self.clicks): accept a Symbol argument.
* ext/tk/lib/variable.rb: be able to set default_value_type; :numeric,
  :bool, :string, :symbol, :list, :numlist or nil (default; same to
  :string). If set a type, TkVariable#value returns a value of the type.
* ext/tk/lib/tkextlib/tclx/tclx.rb: add Tk::TclX.signal to warn the
  risk of using TclX extension's 'signal' command.
* ext/tk/sample/irbtk.rb: irb with Ruby/Tk.
* ext/tk/sample/demos-*/anilabel.rb: bug fix on 'show code'
* ext/tk/sample/demos-*/aniwave.rb: new Ruby/Tk animation demo.
* ext/tk/sample/demos-*/pendulum.rb: ditto.
* ext/tk/sample/demos-*/goldberg.rb: ditto.
* ext/tk/sample/demos-*/widget: add entries of animation demos.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@8048 b2dd03c8-39d4-4d8f-98ff-823fe69b080e