FileModelWatcher should reconcile nested model resources

[ndoschek]

Currently, the FileModelWatcher does not reconcile nested model resources, i.e. model resources contained in a project-like directory are not reconciled if their containing directory is modified/deleted.
If a workspace contains multiple model resources, grouped via project-like directories, the WatchEvents are not correctly applied.
The FileModelWatcher compares the name of the file to be watched (i.e. the resource file name) with the context of the watch event (which is in that case the containing directory name).
We should think of a way to make this event handling more flexible.