mockup for #59,#60, testing #58

It becomes more and more clear that we need to handle the arrays
differently. I strongly believe that we might want to handle them
similar to UA_String, e.g.
```C
struct UA_XXX {
  struct UA_TypedArray {
  	UA_Int32 type; (or UA_VTable* vt)
  	UA_Int32 size; 
  	void** elements;
  }
}
```