Images refactoring

[bethrezen]

• [x] Add relation to product, category, page
• [x] Fetch products, categories, pages with('images')
• [ ] ImgSearch improvements
  • [x] Rename to ObjectImageWidget
  • [x] Fetches from object instance
  • [x] "No image supplied" image for unexisting images(also when image does not exists on fs or thumbnail fn === image_src)
  • [x] Schema.org support
  • [ ] Automatically add ALT+TITLE tag on empty description(turnable off by widget param)
  • [x] Configurable thumbnail sizes list in backend
    • [x] CRUD
    • [x] Background task for recreation(ie. when watermark changed) with support for conditional recreation by id list(by-default - all images)
• [x] Watermark support(configurable in backend)
  • [x] Watermark is binded to each thumbnail size
  • [x] Each size can has unique watermark
  • [x] Overlay mode selection??
• [x] Log of images that doesn't exist
  • [x] Log 404
  • [x] Background task for re-check
  • [x] Frontend & backend link to object(Product, Category or Page) with bad image