fix #2, bug in Diagonal::MaxRowsAtCompileTime when Index==Dynamic
fix #2, bug in Diagonal::MaxRowsAtCompileTime when Index==Dynamic

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