Multiple field attribute

I´ve extendend the K2 Joomlaicons plugin. Previously it was developed by someone else. I made it runnable for Joomla! 3.x. You can see it on my website: http://www.netvisions.eu.

This plugin uses a field with the attribute multiple. Editing an K2 article I can allocate one or more icons to the article with checkboxes. Without this patch it doesn`t work. The selected icons aren`t saved. 

I hope you understand me. If not, feel free to ask me.

Greetings
Carsten