Monodoc.Result now implements IEnumerable

Small usability update for the search results from monodoc. This patch lets you easily enumerate over the results with foreach, in addition to opening up the possibility to use linq.

example usage:
```
RootTree tree = RootTree.LoadTree();

var index = tree.GetSearchIndex ();
var results = index.Search ("string");

foreach (var result in results) {
	Console.WriteLine (result.Title);
}
```