Add setting to filter out zero-arg, non-void/unit methods

```
Sometimes we are only interested in fields and properties, and the methods can 
clutter-up our watch-tree.

For completeness, we could add an option to filter out fields and properties as 
well.
```

Original issue reported on code.google.com by `stephen....@gmail.com` on 21 Jul 2013 at 10:07
- Blocked on: #22
