Preloads directory_watcher glob

This fixes all the issues I have with auto-regeneration. But seeing how this is a elusive bug feedback and testing is welcome!

What it does is simply to preload the directory before scanning it. Somehow this stops the initial repeated auto-regeneration events which may lead to an infinite loop of events.

It also always does an initial build, previously the initial build was triggered 0 or 7 times(No kidding...).

It does not require the latest(broken) version of directory_watcher.