Update player lerpoldxp/yp in gotoposition()

Otherwise, the player would appear to "zip" during the deltaframes
between their previous position and their new position. This did not
happen in the previous game loop order and only happens in the new one.

desktop_version/src/Script.cpp

@@ -306,6 +306,8 @@ void scriptclass::run(void)
 				{
 					obj.entities[player].xp = ss_toi(words[1]);
 					obj.entities[player].yp = ss_toi(words[2]);
+					obj.entities[player].lerpoldxp = obj.entities[player].xp;
+					obj.entities[player].lerpoldyp = obj.entities[player].yp;
 				}
 				game.gravitycontrol = ss_toi(words[3]);