Support {{else}} for empty objects

In order to match the flexibility of using {{else}} with empty arrays, do the same with empty objects!

Sample use case:
data:

```data: { foo: { bar: {} } }```
template:

```
	{{#each foo.bar}}
		{{@key}}: {{.}}<br/>
	{{else}}
		No bar...
	{{/each}}
```

Also works for ```{{#foo.bar:key}}``` & ```{{#if foo.bar}}```
closing block needs to be `{{/each}}`, not `{{/with}}`