The directories used to be always monitored recursively, even when this wasn't
requested, in wxMSW implementation. Change this but also implement efficient
support for monitoring the entire hierarchies using the native support for
this.
Also update the sample to allow monitoring directories recursively as well.
See #12847.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67693 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Merges everything from the branch with only some minor changes, mostly renamed
wxUSE_FSWATCHER_{INOTIFY,KQUEUE} to wxHAS_{INOTIFY,KQUEUE}.
Add wxFileSystemWatcher and related classes.
Also introduces wxEventLoopSource.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62474 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775