0.9.42 "watch the white rabbit"

- [x] **Do as little I/O as possible in the tests** - keep the three tests to make sure events are fired after startWatching(), but the rest of the watcher specs should just mock the actual change
- [x] Go through all Watcher specs, make sure all branches are covered and correct
- [x] Implement Watcher specs

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- [x] Changing a partial doesn't re-render page #134 
- [x] When a folder is renamed, deleted or added, stuff needs to happen #16 
- [x] Changing stylesheets...
- [x] filesystemModel.destroy() should tell outputWriter to remove compiled resource

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- [x] Server / watcher dies if templates or stylesheets are saved #146
- [x] Almost any kind of change crashes the Watcher #147