started to play some enemy death sounds
properly play both enemy death and laser sound
laser volume depends on number of towers
use different sound for creep death.
Also, fixed a bug: tower building payment was hard coded to 10 instead of actual build cost
different creep deaths make different sounds
Also, fiddled around a bit with the tower type values
fiddled with the resource numbers again
Merge branch 'feature/issue/#81_creep_death_sound' into develop