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/copyleft/cgal/assign_scalar.cpp

@@ -0,0 +1,136 @@
+// 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/.
+#include "assign_scalar.h"
+
+IGL_INLINE void igl::copyleft::cgal::assign_scalar(
+  const CGAL::Epeck::FT & cgal,
+  CGAL::Epeck::FT & d)
+{
+  d = cgal;
+}
+
+IGL_INLINE void igl::copyleft::cgal::assign_scalar(
+  const CGAL::Epeck::FT & _cgal,
+  double & d)
+{
+  // FORCE evaluation of the exact type otherwise interval might be huge.
+  const CGAL::Epeck::FT cgal = _cgal.exact();
+  const auto interval = CGAL::to_interval(cgal);
+  d = interval.first;
+  do {
+      const double next = nextafter(d, interval.second);
+      if (CGAL::abs(cgal-d) < CGAL::abs(cgal-next)) break;
+      d = next;
+  } while (d < interval.second);
+}
+
+IGL_INLINE void igl::copyleft::cgal::assign_scalar(
+  const CGAL::Epeck::FT & _cgal,
+  float& d)
+{
+  // FORCE evaluation of the exact type otherwise interval might be huge.
+  const CGAL::Epeck::FT cgal = _cgal.exact();
+  const auto interval = CGAL::to_interval(cgal);
+  d = interval.first;
+  do {
+      const float next = nextafter(d, float(interval.second));
+      if (CGAL::abs(cgal-d) < CGAL::abs(cgal-next)) break;
+      d = next;
+  } while (d < float(interval.second));
+}
+
+IGL_INLINE void igl::copyleft::cgal::assign_scalar(
+  const double & c,
+  double & d)
+{
+  d = c;
+}
+
+IGL_INLINE void igl::copyleft::cgal::assign_scalar(
+  const float& c,
+  float& d)
+{
+  d = c;
+}
+
+IGL_INLINE void igl::copyleft::cgal::assign_scalar(
+  const float& c,
+  double& d)
+{
+  d = c;
+}
+
+IGL_INLINE void igl::copyleft::cgal::assign_scalar(
+  const CGAL::Exact_predicates_exact_constructions_kernel_with_sqrt::FT & cgal,
+  CGAL::Exact_predicates_exact_constructions_kernel_with_sqrt::FT & d)
+{
+  d = cgal;
+}
+
+IGL_INLINE void igl::copyleft::cgal::assign_scalar(
+  const CGAL::Exact_predicates_exact_constructions_kernel_with_sqrt::FT & cgal,
+  double & d)
+{
+  const auto interval = CGAL::to_interval(cgal);
+  d = interval.first;
+  do {
+      const double next = nextafter(d, interval.second);
+      if (CGAL::abs(cgal-d) < CGAL::abs(cgal-next)) break;
+      d = next;
+  } while (d < interval.second);
+}
+
+IGL_INLINE void igl::copyleft::cgal::assign_scalar(
+  const CGAL::Exact_predicates_exact_constructions_kernel_with_sqrt::FT & cgal,
+  float& d)
+{
+  const auto interval = CGAL::to_interval(cgal);
+  d = interval.first;
+  do {
+      const float next = nextafter(d, float(interval.second));
+      if (CGAL::abs(cgal-d) < CGAL::abs(cgal-next)) break;
+      d = next;
+  } while (d < float(interval.second));
+}
+
+#ifndef WIN32
+
+IGL_INLINE void igl::copyleft::cgal::assign_scalar(
+  const CGAL::Simple_cartesian<mpq_class>::FT & cgal,
+  CGAL::Simple_cartesian<mpq_class>::FT & d)
+{
+  d = cgal;
+}
+
+IGL_INLINE void igl::copyleft::cgal::assign_scalar(
+  const CGAL::Simple_cartesian<mpq_class>::FT & cgal,
+  double & d)
+{
+  const auto interval = CGAL::to_interval(cgal);
+  d = interval.first;
+  do {
+      const double next = nextafter(d, interval.second);
+      if (CGAL::abs(cgal-d) < CGAL::abs(cgal-next)) break;
+      d = next;
+  } while (d < interval.second);
+}
+
+IGL_INLINE void igl::copyleft::cgal::assign_scalar(
+  const CGAL::Simple_cartesian<mpq_class>::FT & cgal,
+  float& d)
+{
+  const auto interval = CGAL::to_interval(cgal);
+  d = interval.first;
+  do {
+      const float next = nextafter(d, float(interval.second));
+      if (CGAL::abs(cgal-d) < CGAL::abs(cgal-next)) break;
+      d = next;
+  } while (d < float(interval.second));
+}
+
+#endif // WIN32