Update: Risk Battle Logic

1. Now fully functional and working.

2. Tweaked the algorithm a little bit to fit in a better seiging
scenario where the casualty is supposed to be around 2.5 to 1 or 3 to 1.

3. The new algorithm rolls 4 dies instead of 3, and the attacking
(sieging) side have their number of dice reduced to 3.

4. Small performance improvements in BattleScreen class, with iterator
implementation.