fix bug 475: .exp() now returns +inf when overflow occurs (SSE)
fix bug 475: .exp() now returns +inf when overflow occurs (SSE)

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