Fixed +100% buff issue, change multiplier type to float, add support for more raid sizes

[tegstewart]

Changes proposed:

• Fix issue which caused buffs to be +100% higher than expected
• Changed multiplier type to float to allow finer tuning, ie. if 1 was too hard and 2 was too easy you can now set it to 1.5
• Added support for modern raid sizes (10, 25, 30 man)

Issues addressed: Closes # (insert issue tracker number) None.

Tests performed: (Does it build, tested in-game, etc.) Builds, tested in-game.

Known issues and TODO list: (add/remove lines as needed) None