Building igl statically and moving to the dep scripts

Fixing dep build script on Windows and removing some warnings.

Use bundled igl by default.

Not building with the dependency scripts if not explicitly stated. This way, it will stay in
Fix the libigl patch to include C source files in header only mode.

src/libigl/igl/svd3x3.h

@@ -0,0 +1,40 @@
+// This file is part of libigl, a simple c++ geometry processing library.
+// 
+// Copyright (C) 2013 Alec Jacobson <alecjacobson@gmail.com>
+// 
+// This Source Code Form is subject to the terms of the Mozilla Public License 
+// v. 2.0. If a copy of the MPL was not distributed with this file, You can 
+// obtain one at http://mozilla.org/MPL/2.0/.
+#ifndef IGL_SVD3X3_H
+#define IGL_SVD3X3_H
+#include "igl_inline.h"
+#include <Eigen/Dense>
+
+namespace igl
+{
+  // Super fast 3x3 SVD according to http://pages.cs.wisc.edu/~sifakis/project_pages/svd.html
+  // The resulting decomposition is A = U * diag(S[0], S[1], S[2]) * V'
+  // BEWARE: this SVD algorithm guarantees that det(U) = det(V) = 1, but this 
+  // comes at the cost that 'sigma3' can be negative
+  // for computing polar decomposition it's great because all we need to do is U*V'
+  // and the result will automatically have positive determinant
+  //
+  // Inputs:
+  //   A  3x3 matrix
+  // Outputs:
+  //   U  3x3 left singular vectors
+  //   S  3x1 singular values
+  //   V  3x3 right singular vectors
+  //
+  // Known bugs: this will not work correctly for double precision.
+  template<typename T>
+  IGL_INLINE void svd3x3(
+    const Eigen::Matrix<T, 3, 3>& A, 
+    Eigen::Matrix<T, 3, 3> &U, 
+    Eigen::Matrix<T, 3, 1> &S, 
+    Eigen::Matrix<T, 3, 3>&V);
+}
+#ifndef IGL_STATIC_LIBRARY
+#  include "svd3x3.cpp"
+#endif
+#endif