add: Added Devil agent gamemode, where multiple devils are each trying to buy more souls than the next in line.
add: If you've already sold your soul, you can sell it again to a different devil. You can even go back and forth for INFINITE POWER.
This adds a new gamemode. Devil Agent. It works much like Double Agent, except devils instead of traitors, and instead of killing, the devil simply has to control more souls than the enemy.
Also, whether this is included in the rotation depends on the config settings. By default, it will be disabled.
