close_all_views command + bugfix

The CloseAll method in window.go acted strange. So ive added the following prints:

```go
func (w *Window) CloseAllViews() {
	for _, v := range w.views {
		fmt.Println("new iteration")
		for i, _ := range w.views {
			fmt.Println(w.views[i].Id())
		}
		fmt.Printf("to be removed %d\n", v.Id())
		v.Close()
	}
}
```
```go
func (w *Window) remove(v *View) {
	w.lock.Lock()
	defer w.lock.Unlock()
	for i, vv := range w.views {
		if v == vv {
			fmt.Printf("v: %d vv: %d\n", v.Id(), vv.Id())
			end := len(w.views) - 1
			if i != end {
				copy(w.views[i:], w.views[i+1:])
			}
			w.views = w.views[:end]
			return
		}
	}
	log4go.Error("Wanted to remove view %+v, but it doesn't appear to be a child of this window", v)
}
```

The output was the following:
```
new iteration
324
326
328
to be removed 324
v: 324 vv: 324
new iteration
326
328
to be removed 328
v: 328 vv: 328
new iteration
326
to be removed 328
```
It seems, that the current implementation struggles, when deleting during the iteration. I don't know whats the best alternative, but I tried this approach, which is working:

```go
func (w *Window) CloseAllViews() {
	for len(w.views) > 0 {
		w.views[0].Close()
	}
}
```

If anybody has a better alternative, please let me know. :)
The command should be named "close_all" for ST compatibility