[Major Upgrade] Impartial Leader Selector

[Shad]

The Impartial Leader Selector is back, and it is WAY better.

Improvements:

• Now supports every PG game, including all expansions
  
• Now optionally supports using Black SS leaders in Beyond Normandy, Elsenborn Ridge, and Road to Berlin
  
• User may disallow leaders with "2" modifiers for combat and/or morale
  
• Better back-end for faster results
  

Please thank rerathbun for his tremendous efforts in getting all leaders loaded into our ILS system and for both helping me test the prototypes and proposing design changes.