TkVariable if key name is 'variable' or 'textvariable'
  by default. [ruby-dev:26749]

* ext/tk/lib/tk/{label,radiobutton}.rb: removed its own
  {variable,textvariable} function.

* ext/tk/lib/tk/variable.rb: retains backward conpatibility.

(written by Hidetoshi NAGAI)


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@8933 b2dd03c8-39d4-4d8f-98ff-823fe69b080e