Initial implementation of Sandworms (WIP; Need help with audio and animations)

Using Mailaender's code as basis, this is my implementation of the sandworm behavior. It is still WIP, but you can get an idea of how it looks from the shellmap.
And TS has it (at least when detecting a stealth unit, but is should be able to use the same logic).
But for the moment I suggest we get the logic polished and merged and then I (or anyone else that is more familiar with it) can play around with the sounds. (and with creating logic for the "Enemy unit sighted" notification).