RealQZ: improve computeNorms speed, improve shift accuracy (better to do a/b than a*(1/b)),         update API to set the maximum number of iterations
RealQZ: improve computeNorms speed, improve shift accuracy (better to do a/b than a*(1/b)),
        update API to set the maximum number of iterations

pthulhu/eigen,pthulhu/eigen,pthulhu/eigen,pthulhu/eigen,pthulhu/eigen,cjntaylor/eigen,cjntaylor/eigen,cjntaylor/eigen,cjntaylor/eigen