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.
Mailaender means cache:
```C#
class AttackSwallow : AttackFrontal
{
	readonly Sandworm sandworn;
	public AttackSwallow (Actor self, AttackSwallowInfo attackSwallowInfo)
		: base(self, attackSwallowInfo)
	{
		sandworm = self.Trait<Sandworm>();
	}
```