For watching whole trees - a change which is upcoming - the watch
descriptor IDs will have to be managed in multiple lists. The
InotifyWatchManager encapsulates the managment logic within a nice API.
Instead of using hardcoded fixed width integers, use C integer types.
As the actual integer size of C depends on the implementation, even if
it is often 32bit, we use the C integer types to guard against cases,
where that is not the case.
Each inotify instance produces events for paths in its watch list. Each
item in the watch list is identified by its watch descriptor. Different
paths can be watched for different events.
