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/is_planar.h

@@ -0,0 +1,30 @@
+// 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_IS_PLANAR_H
+#define IGL_IS_PLANAR_H
+#include "igl_inline.h"
+
+#include <Eigen/Dense>
+
+namespace igl
+{
+  // Determine if a set of points lies on the XY plane
+  //
+  // Inputs:
+  //   V  #V by dim list of vertex positions
+  // Return true if a mesh has constant value of 0 in z coordinate
+  //
+  // Known bugs: Doesn't determine if vertex is flat if it doesn't lie on the
+  // XY plane.
+  IGL_INLINE bool is_planar(const Eigen::MatrixXd & V);
+}
+
+#ifndef IGL_STATIC_LIBRARY
+#  include "is_planar.cpp"
+#endif
+#endif