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_stl.h

@@ -0,0 +1,21 @@
+#ifndef IGL_IS_STL_H
+#define IGL_IS_STL_H
+#include "igl_inline.h"
+#include <cstdio>
+namespace igl
+{
+  // Given a file pointer, determine if it contains an .stl file and then
+  // rewind it.
+  // 
+  // Inputs:
+  //   stl_file  pointer to file 
+  // Outputs:
+  //   is_ascii  flag whether stl is ascii
+  // Returns  whether stl_file is an .stl file
+  IGL_INLINE bool is_stl(FILE * stl_file, bool & is_ascii);
+  IGL_INLINE bool is_stl(FILE * stl_file);
+};
+#ifndef IGL_STATIC_LIBRARY
+#  include "is_stl.cpp"
+#endif
+#endif