## Description
Fix various typos in the source code. This includes user facing code, documentation, and source comments. This PR has not been tested.
Closes#1605
* change 'destroyCallback' function to 'resetOnDestroy' boolean parameter
* create a dedicated lambda to reset value to None when object is destroyed and attach it to the target instance
* only way to keep a reference to this function that can be used for destroyed signal (dis)connection with instance accessible
Fix the problem with the application taking up all the CPU after a few reloads while using a Qt3D Scene.
When a file changes, wait for a few milliseconds before adding it back to the watch list. This prevents the system to reload the engine twice for a same fileChanged event (happens with some text editors).
