Import time improvment

Instead of making as many queries as you ps_feature entries (for each
product), it is possible to make it in one query.

And we test if the user has the MySQL rights to create temporary tables.
cleanPositions query update

We now use an unique query, with no need to use temporary table.

Thanks to @sylwit for the tip !
//small fix on Category::cleanPositions()
[+] MO : new module PrestaShop Cleaner: Check and fix functional integrity constraints and remove default data
[-] MO: pscleaner - fixed bugs

We need to know that 'editorial' is a module and not always install (so, table can not be there).

ps2 need to be _DB_PREFIX_ !
[-] MO: followup - fix bug in template vars
Missing php_self variable

Most of the controller have the php_self variable but not the ProductController.
// PR-313
Merge pull request #314 from PrestaEdit/pscleaner

[-] MO: pscleaner - fixed bugs
// remove useless content on 404.php deprecated file
// Small fix (module installation and pscleaner)
// Improved pscleaner
[-] FO : Fix bug #PSCFV-7946 delete customized product with several custos
[-] SQL error in Combination::setAttributes

If $ids_attribute is empty, it cause SQL error.
Update Combination.php
// This reverts commit 9ebe9e189456a93047c0e95c2a7e1a4219563c0e. "Changed modules list button"
// uncomment trigger_error on Tools::throwDeprecated
[-] FO : remove "Invalid address warning" when not "same"  an no invoice address
[-] FO : minimum purchase total with wurrency
[-] Installer: download the language pack even if this is a native language on installation