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_dir.cpp

@@ -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/.
+#include "is_dir.h"
+
+#include <sys/stat.h>
+
+#ifndef S_ISDIR
+#define S_ISDIR(mode)  (((mode) & S_IFMT) == S_IFDIR)
+#endif
+
+#ifndef S_ISREG
+#define S_ISREG(mode)  (((mode) & S_IFMT) == S_IFREG)
+#endif
+
+IGL_INLINE bool igl::is_dir(const char * filename)
+{
+  struct stat status;
+  if(stat(filename,&status)!=0)
+  {
+    // path does not exist
+    return false;
+  }
+  // Tests whether existing path is a directory
+  return S_ISDIR(status.st_mode);
+}