Enable 'watch folder' for custom catalog entries

[pjrobertson]

Fixes #330

I forgot how much of a mess QSLibrarian/QSCatalogEntry actually is :/ This works, but to implement it 'nicely' would require completely rewriting QSLibrarian. Not happening any time soon.

Added new option to sidebar for files & folder catalog type:

To test:

1. Create a new folder catalog entry (e.g. for 'Desktop')
2. Enable the "Automatically update when files change" option
3. Keep your Quicksilver catalog prefs open so you can see the 'count' badge next to your new entry from 1.
4. Create a new file in the folder from 1 (e.g. 'Desktop')
5. Confirm number goes up/down

watch.mov

[pjrobertson]

I'm thinking about this in hindsight: computers are way more powerful now. Should we just do away with the manual rescan for file object sources, and just make all of them update automatically? Or is that asking too much, if someone accidentally adds a folder with a gazillion sub-folders?

[n8henrie]

Or is that asking too much, if someone accidentally adds a folder with a

gazillion sub-folders? The depth limit should still work, right? So this would only be an issue in the case of a gazillion files in a flat structure?

[skurfer]

Should we just do away with the manual rescan for file object sources, and just make all of them update automatically?

The last time someone asked about that, I heard there were limits in the OS for how many files a process was allowed to watch, but I don’t know if that’s still true or what the limit might be.

[pjrobertson]

If this works, I say let's merge it for now. Automatically update all files/folders can come in another update, down the line ;-)