Option to add/remove path after creating

[msangel]

The problem here that per one instance of this we can track single directory(+recursive). So If the amount of tracking candidates vary during program lifecycle, it appears that per each I need create new Instance that will ate another thread.
But we can utilize existed thread that already created during previous instances.
And no, I am not asking for single thread per all, as this may cause StandardWatchEventKinds.OVERFLOW. Many threads is good. 1 thread per 1 folder - not so good. So having some way to alter existed watchers by adding/removing targets is best option.