#10 bug with multiple in SplitSelect

[Stephane Le Solliec]

You have a bug in SplitSelect if you activate multiple
(which is mandatory when you have several dozens of
options).

About half the selected options are passed from A to B
when you click on arrows.

The solution is to add an i-- in the javascript inside
the if (a[i].selected) in the _splitSelectAToB
function. (This is because the a[i] = null destroys an
option in a, hence for example a[15] is destroyed and
former a[16] becomes a[15].)

Thanx for POF, keep up the good work ;-)