[*] - FO - pagination - nbr products/page

It allows to keep a number of 'products per page' related' to original value (PS_PRODUCTS_PER_PAGE).
ex:
Set product per page to '12' (in BO), it display '12','24','36' in the pagination's combo-box, and not '10','12','20','50'

I make this edit in most of my project, it's important in advanced layout (products display by col and not by row like in default template)

(I prefer check if PS_PRODUCT_PER_PAGE is != 0, but with !=10 it keeps original setting (10,20,50))