add eemumu benchmark for 2 channel

benchmark/eemumu/eemumu-1000.sin

+model = SM
+process ee = e1, E1 => e2, E2
+seed = 12345
+
+sqrts = 150 GeV
+
+?vis_history = false
+integrate (ee) { iterations = 5:1000:"gw", 5:1000 }

benchmark/eemumu/eemumu-10000.sin

+model = SM
+process ee = e1, E1 => e2, E2
+seed = 12345
+
+sqrts = 150 GeV
+
+?vis_history = false
+integrate (ee) { iterations = 5:10000:"gw", 5:10000 }

benchmark/eemumu/eemumu-100000.sin

+model = SM
+process ee = e1, E1 => e2, E2
+seed = 12345
+
+sqrts = 150 GeV
+
+?vis_history = false
+integrate (ee) { iterations = 5:100000:"gw", 5:100000 }

benchmark/eemumu/eemumu-1000000.sin

+model = SM
+process ee = e1, E1 => e2, E2
+seed = 12345
+
+sqrts = 150 GeV
+
+?vis_history = false
+integrate (ee) { iterations = 5:1000000:"gw", 5:1000000 }

benchmark/eemumu/eemumu-10000000.sin

+model = SM
+process ee = e1, E1 => e2, E2
+seed = 12345
+
+sqrts = 150 GeV
+
+?vis_history = false
+integrate (ee) { iterations = 5:10000000:"gw", 5:10000000 }

benchmark/eemumu/eemumu-100000000.sin

+model = SM
+process ee = e1, E1 => e2, E2
+seed = 12345
+
+sqrts = 150 GeV
+
+?vis_history = false
+integrate (ee) { iterations = 5:100000000:"gw", 5:100000000 }