Order & cart refactoring

[bethrezen]

Actual details on this task: http://redmine.devgroup.su/issues/4

• [ ] OOP-styled cart
• [ ] OOP-styled order
• [x] Event-based notifications and actions
• [x] Store product price in OrderItem, update it if quantity changes
• [x] Don't empty cart on payment stage #152
• [x] Configurable order workflow #184
• [x] Ability to customize E-Mail notifications for each workflow step, both for managers and buyer in backend(notification templates are stored in plain php files)
• [ ] Configurable option to update product prices of unfinished order on workflow steps
• [ ] Ability to force updating of product prices in backend for order
• [ ] Initiate payment on order with custom price & payment type from backend(if payment handler supports it, ie. for platron)
• [ ] Order creation from backend
• [ ] Adding custom items to order in backend(ie. non-existing products in catalog)
• [ ] Support additional order data(properties)
• [x] Promo Codes, discounts support #124
• [ ] Special case - no products in warehouse
• [ ] Taxes support
• [ ] ShippingOption improvements
  • [ ] Refactor ShippingOption for using unified classes for handling 'Delivery method' + #125
  • [ ] New special delivery type - self-pick from warehouse #174
  • [ ] Support order products total weight
  • [ ] Image for delivery method
  • [ ] Delivery time
  • [ ] Available for user groups
  • [ ] Conditional price calculation
• [ ] Measurement units support for product