Quick PHP plugin code/function change

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Job Description

I need to tweak the included plugin file for Jigoshop (eCommerce site) for Wordpress- it is called Export as CSV. Under the options for export, I had code added to allow for "product category to export". Currently, I can choose the selection "all" or I have to select 1 product category. I need to be able to choose multiple product categories, so I suggested a check box style option menu rather than the drop down style menu.

I need to export to csv data for 2 product categories, or 3 categories depending on the report I am creating. As a result, I need to be able to "multi select" categories to filter the data by. Very similar to the option in the plugin "order statuses to export" where I can choose using check boxes the order statuses to export - i.e. Processing, Pending, etc. That is the concept I need further on the product category export - i.e. embroidery, and custom embroidery.

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