[IMP] m2m_to_x2m: Make operations with SQL
[IMP] m2m_to_x2m: Make operations with SQL

pedrobaeza/openupgradelib,blaggacao/openupgradelib,bwrsandman/openupgradelib,sebalix/openupgradelib,kurkop/openupgradelib,StefanRijnhart/openupgradelib,hbrunn/openupgradelib,OCA/openupgradelib