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/normal_derivative.h

@@ -0,0 +1,44 @@
+// This file is part of libigl, a simple c++ geometry processing library.
+// 
+// Copyright (C) 2015 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_NORMAL_DERIVATIVE_H
+#define IGL_NORMAL_DERIVATIVE_H
+#include "igl_inline.h"
+
+#include <Eigen/Core>
+#include <Eigen/Sparse>
+namespace igl 
+{
+  // NORMAL_DERIVATIVE Computes the directional derivative **normal** to
+  // **all** (half-)edges of a triangle mesh (not just boundary edges). These
+  // are integrated along the edge: they're the per-face constant gradient dot
+  // the rotated edge vector (unit rotated edge vector for direction then
+  // magnitude for integration).
+  //
+  // Inputs:
+  //   V  #V by dim list of mesh vertex positions
+  //   F  #F by 3|4 list of triangle|tetrahedron indices into V
+  // Outputs:
+  //   DD  #F*3|4 by #V sparse matrix representing operator to compute
+  //     directional derivative with respect to each facet of each element.
+  //
+  template <
+    typename DerivedV, 
+    typename DerivedEle, 
+    typename Scalar>
+  IGL_INLINE void normal_derivative(
+    const Eigen::PlainObjectBase<DerivedV> & V,
+    const Eigen::PlainObjectBase<DerivedEle> & Ele,
+    Eigen::SparseMatrix<Scalar>& DD);
+}
+
+#ifndef IGL_STATIC_LIBRARY
+#  include "normal_derivative.cpp"
+#endif
+
+#endif
+