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and test it on ruby 2.0.0p481, update some outdated testcase/example.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 ?

@windwiny you didn't install DevKit then, simply because `devkit.rb` will be copied when `dk.rb install` is executed if you followed DevKit instructions.