[fixed] GZDoom's Strife Grenade Physics Don't Match ZDoom's

[Deathlike2]

Title says it all.

Then again.. I've reported how the grenades should actually work in a ZDoom bug report...

http://forum.zdoom.org/potato.php?p=188583

I'm not sure if it is related.. but when you shoot the grenades into the air.. they "explode" in mid-air.. when it should never do that...

[Graf Zahl]

Fixed. I tried to be too precise but never realized that one piece of the code didn't work.
As a result they exploded when hitting the ceiling.