scripting: if...else if...else Statement

Change-Id: Ia60b352b4cb52d2712b2499550859ece699341d1
Reviewed-on: https://gerrit.libreoffice.org/11322
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>