Improved model query
Only allow to set enabled product fields in the model
Finally added method to get the real product ID (not variant ID)
Customer defined fields cannot be saved in the product model
Added method to check if product is a variant
Passing additional parameters to the URL does not make sense

Not used anyway
Use helper method
Auto-Update collection only in the frontend
$arrOptions is optional
Fixed ajax response in product list
Improved backend intro message design
Make sure options is an array
Use helper method
Do not modify product model with variant data, use variant product
Options are stored in the product data
Fixed media data merging
Do not reload the database record again