* refactoring of Product:

* use ProductReturnType<>::Type to get the correct Product xpr type
  * Product is no longer instanciated for xpr types which are evaluated
  * vectorization of "a.transpose() * b" for the normal product (small and fixed-size matrix)
  * some cleanning
* removed ArrayBase

bench/basicbenchmark.cpp

@@ -4,7 +4,7 @@
 
 int main(int argc, char *argv[])
 {
-  // disbale floating point exceptions
+  // disable floating point exceptions
   // this leads to more stable bench results
   // (this is done by default by ICC)
   #ifndef __INTEL_COMPILER