Prevent -generation when long overflow for antimatter gen.

[lordIcocain]

No description provided.

[RecursivePineapple]

@lordIcocain It looks like this just moves the problem a bit. Is it possible for the generation to be high enough that it wraps around to >0 again?
I'd prefer to see an addition util method that will return Long.MAX_VALUE when normal addition would wrap instead of this, but if it won't ever wrap around to >0 then this solution is fine.

[lordIcocain]

@RecursivePineapple i didn't test with super high generations, but it's on non-standard use category. My goal is prevent overflow for situation when you want to generated as close to long max as possible.