Given a set $P = \{p_1, \dots, p_n\}$ of points in $\mathbb R^2$, where $p_i = (x_i, y_i)$, compute the parameter vector $\theta = (\theta_1, \theta_2)$ that minimizes the median of the squared residuals (where a residual is defined as $y_i - x_i\theta_1 - \theta_2$).