This change makes a distinction between no_hosts_matched and no_hosts_remaining.
In both cases we do not start facts-gathering, or run any tasks.
In the case that there are no more hosts remaining, we abort running tasks and abort the playbook.
I also cleaned up the leftovers from the previous patchsets, as these are no longer required.
This closes#1187.
Example playbook:
```yaml
---
- hosts: emptygroup
tasks:
- action: command date
- action: command false
- hosts: all
gather_facts: False
tasks:
- action: command ls
- action: command false
- action: command true
- hosts: all
tasks:
- action: command true
- action: command false
- hosts: all
tasks:
- action: command pwd
```