We don't have any available icon packs except the basic one.
For example you can replace the icons with Font awsome Icons
if you include the script to your template and afterwards you can do something like :
Actually it's a good idea but it doesn't work entirely. The first icon is well replaced but the second one makes the menu element title disapearing (just the icon is displayed).
Another solution I found was to create my own icons png and uploaded them into the template icon images folder then I use the default icon manager from the menu settings.