Another edge case for #466

[gregorgorjanc]

@janaobsteter another try

Now I get this

> createMultiColony(n = 10)
An object of class "MultiColony" 
Number of colonies: 10 
Are empty: 10 
Are NULL: 10 
Have split: 0 
Have swarmed: 0 
Have superseded: 0 
Have collapsed: 0 
Are productive: 0 
> 
> createMultiColony(n = 0)
An object of class "MultiColony" 
Number of colonies: 0 
Are empty: 0 
Are NULL: 0 
Have split: 0 
Have swarmed: 0 
Have superseded: 0 
Have collapsed: 0 
Are productive: 0 

Let's see if we need to cater for any more edge cases. Damn NULL's!