File monitor threading.

[Daniel Moodie]

Hi all,

I recently discovered a bug in my code and I'd like confirmation / to let you guys know about it so know one beats their head into the wall for a few hours unnecessarily.

The file monitoring code can be called form different threads on Linux without a problem, but on windows FileWatcherWin32::update needs to be called from the same thread that called FileWatcherWin32::addWatch, otherwise the callback is never called.