Created isMultiSelect function on the SelectBoxFilter

Created isMultiSelect function on the SelectBoxFilter.
This will be a wrapper for the listBox.isMultipleSelect();.

issue A24Group/Triage#3759
Merge remote-tracking branch 'upstream/master' into isMultiSelect
Fixed function name

Fixed function name

issue A24Group/Triage#3759
Merge pull request #204 from Rynoh/isMultiSelect

Created isMultiSelect function on the SelectBoxFilter