Update oxsession.php and loads oxBasket through oxNew()

The moved line "$oEmptyBasket = oxNew('oxbasket');" was an old design flaw. The old line leads to an intialization through oxAutoload because the unserialize() is called first, but normally, every class is initialized through oxNew(). This can break modules. (Broke mine many times!)
Merge pull request #22 from WBL-BjoernLange/b-dev-ce

0004262: Change in oxSession::getBasket leads to sideeffect in oxutilsobject::_makeSafeModuleClassParents: 
Update oxsession.php and loads oxBasket through oxNew()