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and test it on ruby 2.0.0p481, update some outdated testcase/example.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

@luislavena , i'm not clear.

I'm use 7z format install ruby2.0 , and install DevKit 4.7.2, `require  'devkit'` will throw LoadError. 

If not need `devkit gem`, just comment this line or use other method check DevKit.