Synchronization should be only based only on id

Magento API is a litlle weird and by default if you ask something like a product with an id, magento will check in the sku and in id.
And so sometime when you ask for a product, you have an another product :(
Since 1.4 magento give the possibility to force the identifier. We should pass it everythere in order to avoid this kind of error.
The problem is that this option (I think is required to avoid stupid error) is always the last parameter of each method :( and so we have to pass all useless params for each call :(.
As openerp support onfly import (function extid_to_oeid in base_external_referentials) add all of this useless params is not so easy. So I propose 2 solutions
- Never using magento API, and create a real magento api so we don't have to pass useless params.
- Or giving the possibility to store the useless params in the mapping (we already store the method, maybe we can store the defaults params and build the request correctly)