Allow "procedural" shapekey drivers by pointing driver's 'self' to evaluated object

Shape keys for flower petals, pine cones and needles, animated leaves, candle flames, bugs etc. - they have to be controlled by drivers, as otherwise is impractical. And their drivers have to be mass applicable (copy-paste), which implies use of "self" pointer when each objects position matters (and it usually does in mentioned cases). Unfortunately, currently 'self' pointer of Shape Key points to shape key object with no way of accessing data of the owner object that is being evaluated.