* Add the possibility to customize the output of matrices, e.g.:

IoFormat OctaveFmt(4, AlignCols, ", ", ";\n", "", "", "[", "]");
   cout << mat.format(OctaveFmt);
  The first "4" is the precision.
  Documentation missing.
* Some compilation fixes

Eigen/Core

@@ -4,6 +4,7 @@
 #include "CoreDeclarations"
 #include <iostream>
 #include <cstring>
+#include <string>
 
 #ifdef EIGEN_VECTORIZE
 // it seems we cannot assume posix_memalign is defined in the stdlib header