Pretty print events and properties while implementing interface

Fix #397.

Events now are printed as follows:

```fsharp
let _ = { new IMyEvent<int> with
              [<CLIEvent>]
              member x.M: IEvent<int> = 
                  raise (System.NotImplementedException())
        }
```

Getters are printed as follows:

```fsharp
member x.Count: int = 
     raise (System.NotImplementedException())
```

Getters and setters are merged under the same identifier:

```fsharp
member x.Item
      with get (): string = 
          raise (System.NotImplementedException())
      and set (v: string): unit = 
          raise (System.NotImplementedException())
```