added another tank theme using the nemesis track. much shorter and would normally play in survival mode

added a new tank theme to go with the halo feel. but this is a work in progress so the normal tank theme might pop up on occassion

fixed the volume of the flood tank's pain sounds. that way the player can hear them more clearly over the music volume

fixed the death sounds, fixed the volume.

fixed the tank yell to match the sounds the Flood tank makes