Auto file reload should only do so when the file is in focus

[jlacasse]

I find it very annoying that if I have a file open but not the file in focus and it gets changed by some other program that it gets updated at that moment causing the screen to flicker momentarily. Also if the file is very large, it causes the editor to hang until it's done reloading it. The editor should only check to see if a file needs to be reloaded when that file comes into focus or at least it should be a setting.