Returns the probability \(\outsurv\) that a person with mortality curve MortHandle1 outsurvives a person with mortality curve MortHandle2 given both are alive at age \(a=\)Age (Vaupel et al 2021). Outsurvival is given by the integral \begin{equation} \outsurv=\frac{1}{\sfrac_1(a)\sfrac_2(a)}\int_a^\omega \force_2(x)\sfrac_2(x)\sfrac_1(x)dx . \end{equation} If Age is not specified it defaults to 0. Omega specifies the upper limit of the integral. If not specified it defaults to Omega=120.