revert to symbols

Parfait::Words were nice, but endless problems with the fact that when
you write “String” you get a string.
Symbols take care of uniqueness at the same time

lib/parfait.rb

@@ -13,6 +13,3 @@ require "parfait/layout"
 require "parfait/message"
 require "parfait/frame"
 require "parfait/space"
-
-#if we are in the ruby run-time / generating an executable
-require "virtual/parfait_adapter"