fix bug in tyre effects and its test

src/monocoque/devices/hapticeffect.c

@@ -390,7 +390,7 @@ double slipeffect(SimData* simdata, int effecttype, int tyre, double threshold,
     {
         return 0;
     }
-    if(simdata->Zvelocity > 1 || simdata->Zvelocity < -1)
+    if(simdata->Zvelocity > 1)
     {
         return 0;
     }

src/monocoque/gameloop/gameloop.c

@@ -787,6 +787,9 @@ int tester(SimDevice* devices, int numdevices)
     simdata->tyrediameter[1] = -1;
     simdata->tyrediameter[2] = -1;
     simdata->tyrediameter[3] = -1;
+    simdata->Xvelocity = 0;
+    simdata->Yvelocity = 100;
+    simdata->Zvelocity = 0;
 
     sleep(3);