FIX impossible to import custom attributes via XML

The validation for the field custom fail due the missing node in the xsd declaration.
After this small fix the import with custom attributes runs without any problem using the node:

<custom code"yourCustomAttribute">yourCustomValue

Lazy loading option values and cache manager

Existing option values are now only loaded per attribute, when it is needed.
Newly created option values are given the sort order that matches their position.

The cache manager allows you to refresh any of product importer's caches.

Option value speed-up

Category info and option values are no longer reloaded from the database every batch.
Newly created option values are given a fixed sort order of 10000.

Make missing links non-fatal

Special case: if product A links to product B (for instance upsell), A and B in the same batch, and product B could not be created, the importer threw an exception up until now. I thought this could only occur in case of importer error, but apparently it also occurs when the input data is wrong. Therefore adding an error to product A suffices. Product A is still imported, but without the reference to the non-existing product B.

Import images with delete; imports with unknown type

1. By default, the importer does not delete images. Images are only added and updated.

If you want the importer to delete existing product images that are not present in the current import, use this

 $config->imageStrategy = ImportConfig::IMAGE_STRATEGY_SET;

This will set images as they are named in the import. However, the importer will still not remove all images if none are added to a product. This is a safety precaution.

2. If the product type is unknown, you can ask the library for the Product, by giving the sku:

   $product = $importer->getExistingProductBySku($sku);

or the id

$product = $importer->getExistingProductById($id);    

The importer will return an object with the correct class, or false if no product with the id or sku could be found.

Same as 1.2.1

1.2.0

Extra check if image is not used by other product

Remove version from composer.json

composer.json should not have a version when the package uses tags

Fix for duplicate images

Images with _[d]. (where [d] is a series of decimals) in the filename were duplicated on updates.

Added the option to remove category path url-rewrites.

If a shop does not use category paths in its urls, url_rewrite generation can be simplified a lot. This saves time and reduces the size of the url_rewrite table.

Public release

1.0.0

doc: installation