Updated throw reason for IndexOutOfBoundsException

Previously, the reason was when the provided index is > 4, whereas it should be > 3.
Merge #47

Thanks @DomWilliams0

commit b6565222379f3042e78ba7a1b934d0632141f518
Author: Dom W
Date:   2013-10-13 19:26:13 +0100

Updated throw reason for IndexOutOfBoundsException

Previously, the reason was when the provided index is > 4, whereas it should be > 3.