Move updating lerpoldxp/yp to start of gamelogic()

The previous location of this loop was placed there because it happened
just after the end of the render function. Now that the loop order is
fixed, the first thing that happens after the render function is the
start of gamelogic(), so this loop should go there now, else entity
positions won't be interpolated.

Also it now preincrements instead of postincrements because I like
preincrements.

desktop_version/src/Logic.cpp

@@ -122,6 +122,13 @@ void gamecompletelogic2(void)
 
 void gamelogic(void)
 {
+    /* Update old lerp positions of entities */
+    {size_t i; for (i = 0; i < obj.entities.size(); ++i)
+    {
+        obj.entities[i].lerpoldxp = obj.entities[i].xp;
+        obj.entities[i].lerpoldyp = obj.entities[i].yp;
+    }}
+
     //Misc
     if (map.towermode)
     {