remove() does not handle references correctly

[AntonBogun]

The code

let l=[[1],[2]]
l.remove(0,2)
print(l)

results in a post-execution warning:
LEAKS FOUND (this indicates cycles in your object graph, or a bug in Lobster)
_-1_ = [2]

Note that the same applies when using strings, but not integers, which leads me to believe that this is an issue only with referenced values.

[Wouter van Oortmerssen]

Fixed here: 8071024