成员的完整列表，这些成员属于 vde::sketch::ConstraintSolver,包括所有继承而来的类成员

add_circle(int center, double radius)	vde::sketch::ConstraintSolver
add_constraint(ConstraintType type, const std::vector< int > &elements, double val=0.0)	vde::sketch::ConstraintSolver
add_line(int p0, int p1)	vde::sketch::ConstraintSolver
add_point(double x, double y, bool fixed=false)	vde::sketch::ConstraintSolver
degrees_of_freedom() const	vde::sketch::ConstraintSolver
fix_point(int pid)	vde::sketch::ConstraintSolver	inline
get_point(int id) const	vde::sketch::ConstraintSolver
points() const	vde::sketch::ConstraintSolver	inline
solve(int max_iter=100, double tol=1e-8)	vde::sketch::ConstraintSolver