small comments to make code more readable
Behaviour registration have been refactored.

- Less technical debt, smarter code, better looking.
- Moved from a monstruons hash structure { :like => { :on => [azerty],
  :via => }} to this convention { :like => [[actor1,target1,(medium1)],[actor2,target2,(medium2) ... ]] }
bumped version to 0.2.6