Refactored manifest onStart/onStop to onCreate/onDestroy (#195)

When writing documentation, I realized how `onStart`/`onStop` isn't clearly communicating what it does (it could imply show/hide), so I renamed it to `onCreate` and `onDestroy`.

Tactility/Source/app/boot/Boot.cpp

@@ -97,7 +97,7 @@ public:
         }
     }
 
-    void onStop(AppContext& app) override {
+    void onDestroy(AppContext& app) override {
         thread.join();
     }
 };