patchx

Hi, @luislavena

I change exerb-mingw into a gem;

and test it on ruby 2.0.0p481, update some outdated testcase/example.

Can you check example/vruby and example/rubytk ? how to packaged tcl file to exe ?

Maybe use other method check `RubyInstaller's DevKit` ? like check `%x{gcc -v}` ?

the `require 'devkit'` is just require `devkit` gem.