Refactor folder (#10475)

Move many third-party components' source codes from the src folder to a new folder called deps_src. The goal is to make the code structure clearer and easier to navigate.

deps_src/libigl/igl/get_seconds.cpp

@@ -0,0 +1,15 @@
+// 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/.
+#include "get_seconds.h"
+#include <chrono>
+IGL_INLINE double igl::get_seconds()
+{
+  return 
+    std::chrono::duration<double>(
+      std::chrono::system_clock::now().time_since_epoch()).count();
+}