YITH WooCommerce PDF Invoice 4.16.0

* Tweak: Get all the data from the orders
* Tweak: Improving the plugin settings
* Tweak: Now the footer can use the postmetas placeholders
* Tweak: Fees also added to the invoice subtotal
* Tweak: Adding the dimension option of the packing slip in the template, removing it from the class
* Update: Spanish translation
* Update: Updating Plugin Framework
* Update: updated the official documentation url of the plugin
* Fix: Fixed a problem when create the documents in the order table
* Fix: fixing the round in the details template
* Dev: checking YITH_Privacy_Plugin_Abstract for old plugin-fw versions
* Dev: Working in a new tab of the settings
* Dev: Hiding the new fields name tab
* Dev: hiding the postmetas created in the order
* Dev: added and old version of the get_order_currency functions to avoid incompatibilities

* New: Support to WooCommerce 3.4.0
* GDPR:
- New: exporting user additional uploads data info
- New: erasing user additional uploads data info
- New: privacy policy content
* New filter yith_ywpi_print_invoice_name
* New: Show packing slip in a new tab
* Tweak: Remove blank lines in $replace_details
* Update: Update language files .pot
* Update: Italian translation
* Update: Dutch translation
* Update: documentation link of the plugin
* Fix: fixing a warning with non numeric value
* Fix: fixed a problem when generate credit notes
* Fix: fixed a php warning
* Dev: added a new filter in replace details
* Dev: added filter ywpi_get_item_product_regular_price

Tweak: Now in the orders table the download button open a new tab if needed
Tweak: show one meta for row in invoice in case of variable products
Dev: Added a filter to get the order currency
Dev: new filter 'yith_ywpdi_mpdf_args'
Fix: Fixing problem with order currency in the Invoices
Fix: Fixing the currency issues in the invoices and packing slip
Fix: Fixing the currency method
Fix: Percentage tax of the shipping on the invoice
Fix: Percentage tax of the shipping on the invoice (remove the wc_round_tax_total)
Fix: Force wp_redirect if wp_safe_redirect not works.