fix a copy&paste error on check for movement stop if opposite controls are pressed (#564)

src/js/pannellum.js

@@ -1267,7 +1267,7 @@ function keyRepeat() {
     }
     
     // Stop movement if opposite controls are pressed
-    if (keysDown[0] && keysDown[0]) {
+    if (keysDown[0] && keysDown[1]) {
         speed.hfov = 0;
     }
     if ((keysDown[2] || keysDown[6]) && (keysDown[3] || keysDown[7])) {