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/signed_angle.h

@@ -0,0 +1,27 @@
+#ifndef IGL_SIGNED_ANGLE_H
+#define IGL_SIGNED_ANGLE_H
+#include "igl_inline.h"
+#include <Eigen/Dense>
+namespace igl
+{
+  // Compute the signed angle subtended by the oriented 3d triangle (A,B,C) at some point P
+  // 
+  // Inputs:
+  //   A  2D position of corner 
+  //   B  2D position of corner 
+  //   P  2D position of query point
+  //   returns signed angle
+  template <
+    typename DerivedA,
+    typename DerivedB,
+    typename DerivedP>
+  IGL_INLINE typename DerivedA::Scalar signed_angle(
+    const Eigen::MatrixBase<DerivedA> & A,
+    const Eigen::MatrixBase<DerivedB> & B,
+    const Eigen::MatrixBase<DerivedP> & P);
+}
+#ifndef IGL_STATIC_LIBRARY
+#  include "signed_angle.cpp"
+#endif
+#endif
+