Redefine the antag/sec ratio

[mralexs]

I think it would help if there was a way to practice being an antag. A common complaint is that not a lot of people have experience being one, whereas it's easy to get sec experience. Another problem is that some antags want to go loud immediately, leading to sec coming down on them with extreme prejudice. Some players who have tons of experience in rampaging can get away with this, but not many new players can and they want to.