Convenience improvement: Offer to set initial guess as matrix
Input: Matrix of shape NX x NUM_TRAJ_POINTS, ascending time from left to right (like output format of solution_reshaped()).
inline void x_guess_reshaped(const Eigen::Ref<const Eigen::Matrix<scalar_t, nx, num_nodes>>& x_guess_mat) noexcept
{
m_solver.m_x.template head<varx_size>() = Eigen::Map<const traj_state_t>(x_guess_mat.rowwise().reverse().eval().data(), nx*num_nodes);
}