E.g.:
```
> foo
> bar
{.myclass}
```
There are some current limitations: For tables you can currently only apply it to the full table, and for lists the ul/ol-nodes only, e.g.:
```
* Fruit
* Apple
* Orange
* Banana
{.fruits}
* Dairy
* Milk
* Cheese
{.dairies}
{.list}
```
Fixes#7548
