Various compilation fixes for MSVC 9. All tests compile but some

still fail at runtime in ei_aligned_free() (even without vectorization).

Eigen/Geometry

@@ -3,6 +3,10 @@
 
 #include "Core"
 
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
+
 namespace Eigen {
 
 /** \defgroup Geometry Geometry module