Refactoring visibility related events

1. remove unnecessary events from MainViewModel
2. remove usage of Obsolete api (show, hide etc)
3. fix space problem in #660
4. part of #486
5. fix up/down key bug introduced in 92b7ca6a1bafd254e39ee92812ff691906cd85c1
6. fix #678

Wox.Plugin/IPublicAPI.cs

@@ -31,11 +31,13 @@ namespace Wox.Plugin
         /// Just change the query text, this won't raise search
         /// </summary>
         /// <param name="query"></param>
+        [Obsolete]
         void ChangeQueryText(string query, bool selectAll = false);
 
         /// <summary>
         /// Close Wox
         /// </summary>
+        [Obsolete]
         void CloseApp();
 
         /// <summary>
@@ -46,11 +48,13 @@ namespace Wox.Plugin
         /// <summary>
         /// Hide Wox
         /// </summary>
+        [Obsolete]
         void HideApp();
 
         /// <summary>
         /// Show Wox
         /// </summary>
+        [Obsolete]
         void ShowApp();
 
         /// <summary>
@@ -69,11 +73,13 @@ namespace Wox.Plugin
         /// <summary>
         /// Show loading animation
         /// </summary>
+        [Obsolete("automatically start")]
         void StartLoadingBar();
 
         /// <summary>
         /// Stop loading animation
         /// </summary>
+        [Obsolete("automatically stop")]
         void StopLoadingBar();
 
         /// <summary>