Weapon stats modifications

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The stats of some weapons have been modified:
- SMG is a little bit more powerful now (10 instead of 9 hp)
- KV9, Plasmarifle, Laserforce, Crossbow, AP Ripper, Enhanced Pulsar, R51 and KR-90 have less freezing time (most of the time 0.05 seconds less)

I'm not sure about the other weapons, don't want to make some weapons too powerful either.