Fixed concatenation error

[truj]

I adjust itemsPerPage dynamically via select box. While using the initial value everything was fine. But after changing itemsPerPage, the new perPage value was a string. So the result of end = start + perPage was much too high on any page other than 1.

[michaelbromley]

Good catch, thanks. I'll write some tests for this case and it'll be in the next release. 👍