vector.resulting()

During development of my cars mod which uses the vector functions here and there, I noticed that there is no function which merges an undefined amount of vectors in a single one.

![res](https://cloud.githubusercontent.com/assets/2469742/3095136/0b299330-e5c4-11e3-8b5f-0696313f1fa6.jpg)

So I decided to code it on my own, saw that it works and thought I should share it :)

Code example:
```lua
local vectors = {
	{x = 5, y = 0, z = -5},
	{x = -5, y = 10, z = 8}
}

=> {x = 0, y = 10, z = 3}
```