Getting rid of singleton class modification in Shoes::App
Getting rid of singleton class modification in Shoes::App

- also moved window into the app class, as per manual it can only
  be called from there
- removed the whole @owner modification part and just added a to_s
  method to the App, as only apps seem to be able to be parents
  of other apps.

thescientician/lightning-timer,thescientician/lightning-timer,thescientician/lightning-timer