Added libigl library files (header-only library)

xs/src/igl/C_STR.h

@@ -0,0 +1,18 @@
+// 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_C_STR_H
+#define IGL_C_STR_H
+// http://stackoverflow.com/a/2433143/148668
+// Suppose you have a function:
+//   void func(const char * c);
+// Then you can write:
+//   func(C_STR("foo"<<1<<"bar"));
+#include <sstream>
+#include <string>
+#define C_STR(X) static_cast<std::ostringstream&>(std::ostringstream().flush() << X).str().c_str()
+#endif