change default show delay to 0ms

--the reason is the plasma default behavior
for touch gestures under X11. Many users
report that Latte isnt working correctly
with left edges. Latte isnt responsible for
this but the plasma touch gestures implementation.
By changing the default for our Show Timer to
0ms then the situation is improved a bit more
for such cases and the user of course can
always alter its value from dock settings
window.

-https://github.com/psifidotos/Latte-Dock/wiki/F.A.Q.#q-my-left-dock-behaves-strangely-from-plasma-510-and-beyond-can-i-fix-this

-https://bugs.kde.org/show_bug.cgi?id=392464
-https://bugs.kde.org/show_bug.cgi?id=382219

app/visibilitymanager.cpp

@@ -475,7 +475,7 @@ inline void VisibilityManagerPrivate::restoreConfig()
         return;
 
     auto config = view->containment()->config();
-    timerShow.setInterval(config.readEntry("timerShow", 200));
+    timerShow.setInterval(config.readEntry("timerShow", 0));
     timerHide.setInterval(config.readEntry("timerHide", 700));
     emit q->timerShowChanged();
     emit q->timerHideChanged();