Improved order import, wysiwyg editor, validation and special role for allegro images

• Fix problem with copying data from quote to sales_order on Magento 2.3.3 (#22)
• Use ExtensionAttributesInterface for setting data in quote table
• Allow orders that are not paid yet to be imported (#19)
• Allow only orders with state new to be updated
• Improve wysiwyg editor fulfill allegro validation specs (#21)
• Add a special image role to choose which image to add to the create offer form (#14)
• Update documentation (#14)
• Set default value for delivery handling time in create offer form
• Add offer name length counter and validator
• Completing the documentation with automatic status update on Allegro