fix nil comparison error, see issues 470 and 601

this is fairer

Use tr() properly

This is something we need to check in all translations. Occasionally the source phrase ends w/ a space. Need to make sure translations take this into account.

So. First pass. Add secondary explosions to RateExplosion and RateShotgun. Not yet added to shoves. This is of limited utility at present since the dX has to be small since we can't bother tracing all hog motion. But, should be more useful once shove is added, and tracking of explosives and mines.

Don't use writeln in ai thread (from rdd4035ee0f12), this causes crashes. Fixes issue #617.

aaaaand this one never was damaging

cheezemonkey pointed out this is no longer damaging

yep. I did forget to put this back

So. This should fix ammo delays being off on a team that is resurrected later in the game, even up freezing delays a bit, prevent an infinite loop in freezing, and reduces fuel burn when adjusting freezer to one-fourth.