many small fixes and documentation improvements,
this should be alpha5.
diff --git a/doc/snippets/compile_snippet.cpp.in b/doc/snippets/compile_snippet.cpp.in
index bc79e25..1164b9d 100644
--- a/doc/snippets/compile_snippet.cpp.in
+++ b/doc/snippets/compile_snippet.cpp.in
@@ -1,4 +1,5 @@
 #include <Eigen/Core>
+#include <Eigen/LU>
 USING_PART_OF_NAMESPACE_EIGEN
 using namespace std;
 int main(int, char**)