several small changes

dirt change, dirt pops ups less often due to chance of increasal instead
of direct increase (rohane dirt request)
fueltanks shouldnt create big explosions anymore by default, it removes
a tile which creates alot of grief(suggested by Icecream and Honey,
confirmed by rohane)
Change in the icons of the adult Diona (sandcoms request)
final AI interface stuff

Added the announcements system to the AI interface