Added summation of kernels under the state space formalism.
Added summation of kernels under the state space formalism.

SheffieldML/GPy,esiivola/GPYgradients,ysekky/GPy,esiivola/GPYgradients,dhhjx880713/GPy,befelix/GPy,esiivola/GPYgradients,befelix/GPy,befelix/GPy,ysekky/GPy,dhhjx880713/GPy,ysekky/GPy,esiivola/GPYgradients,avehtari/GPy,dhhjx880713/GPy,befelix/GPy,avehtari/GPy,SheffieldML/GPy,mikecroucher/GPy,mikecroucher/GPy,avehtari/GPy,avehtari/GPy,mikecroucher/GPy,mikecroucher/GPy,ysekky/GPy,SheffieldML/GPy,dhhjx880713/GPy,SheffieldML/GPy