- removed every references to the gameobserver singleton. This object can now be instantiated several times as it's needed for minmax. To be able to do that, I mostly added a reference to a gameobserver from any targetable object (cards, players, spells) and abilities.
- In order to clarify getEfficiency, started creating "getEfficiency" functions specific to each type of ability (see example with Damager). This won't reduce the file size but should make things bit clearer
- Minor cleanup of getEfficiency
- bug fixes in getEfficiency