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/null.h

@@ -0,0 +1,36 @@
+// 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_NULL_H
+#define IGL_NULL_H
+#include "igl_inline.h"
+
+#include <Eigen/Dense>
+
+namespace igl 
+{
+  // Like MATLAB's null
+  //
+  // Compute a basis for the null space for the given matrix A: the columns of
+  // the output N form a basis for the space orthogonal to that spanned by the
+  // rows of A.
+  //
+  // Inputs:
+  //   A  m by n matrix
+  // Outputs:
+  //   N  n by r matrix, where r is the row rank of A
+  template <typename DerivedA, typename DerivedN>
+  IGL_INLINE void null(
+    const Eigen::PlainObjectBase<DerivedA> & A,
+    Eigen::PlainObjectBase<DerivedN> & N);
+}
+
+#ifndef IGL_STATIC_LIBRARY
+#  include "null.cpp"
+#endif
+
+#endif