EDS - Extended Delivery System

Hi

This is not a real pull request, I'll make a new one, with only one commit later, once this has been tested more.
This is my latest project. I believe it is finished, so now it's need to be tested.
So if anyone would be so kind to give it a go, it would be much appreciated.
Everything I though of to test, works great.
But I probably missed stuff, so please test anything you can think of.

If you look under Preference -> Orders there is EDS options and a version number. This version number is only to keep track of testing during development  

Feel free to suggest code improvements, report where I break code norms or anything else.

Quick Changelog
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Support for multiple Delivery Slips
Support for multiple Invoices based on Delivery Slips
Added packingslip
Added a new delivery-slip design
Option to set default invoice/delivery slip
Option to add product img to packingslip
Added partial shipped status
Added options to attach invoice / delivery pdf to email at statuses
Added option to only email latest invoce / delivery as attachment
Added due date to invoice and option to enable/disable it
Added Sample order template and options
Added option to set invoice template for each order
Packingslip automaticly only shows undelivered proucts

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@PrestaShop team: GitHub says it can't auto merge my branch with yours. So I assume there is some conflict somewhere. Please let me know what, and I'll fix it.