Solves installation failures for packages like `bonnie++` or
`virtualhost.sh` as described in #8413.

Handle the case where include_pattern and exclude_pattern exist but are empty strings

need to handle the case where include_pattern and exclude_pattern exist in the config file but contain empty strings

Fix issue #8578. Setting envvar in ""'s ensures the PYTHONPATH is set to

include the lib/ directory.

Before - PYTHONPATH is empty.. ansible fails to run

    $ source hacking/env-setup.fish
    Appending PYTHONPATH

    Setting up Ansible to run out of checkout...

    PATH=/Volumes/opt/src/ansible/bin /usr/local/share/python3 /usr/local/bin
    /usr/bin /bin /usr/sbin /sbin /usr/local/bin /opt/X11/bin /usr/bin /sbin
    /usr/local/bin /Users/ms/bin/
    PYTHONPATH=
    ANSIBLE_LIBRARY=/Volumes/opt/src/ansible/library
    ...

    Traceback (most recent call last):
      File "/Volumes/opt/src/ansible/bin/ansible", line 25, in <module>
          from ansible.runner import Runner
          ImportError: No module named ansible.runner

After change - it's set.. ansible runs.

    source hacking/env-setup.fish
    Appending PYTHONPATH

    Setting up Ansible to run out of checkout...

    PATH=/Volumes/opt/src/ansible/bin /usr/local/share/python3 /usr/local/bin
    /usr/bin /bin /usr/sbin /sbin /usr/local/bin /opt/X11/bin /usr/bin /sbin
    /usr/local/bin /Users/ms/bin/
    PYTHONPATH=/Volumes/opt/src/ansible/lib:
    ANSIBLE_LIBRARY=/Volumes/opt/src/ansible/library
    ....

    $ ansible
    Usage: ansible <host-pattern> [options]

ansible-vault should support script for --vault-password-file too

Fixes #8317

Fix typo in CHANGELOG.md

This change occured int he ec2 module, not ec2_vol

Fixes 8362, returns stderr if No space left on device

Also refactors playbook loading code relating to vars in playbooks
to a sub-function.

Fixes #8534

Replace all occurrences of "Digital Ocean" with "DigitalOcean"

Also adds integration tests for nested includes with conditionals

Add spaces between sentences in formatted docs.

Fixes #8538

wait_for module: check e.errno instead of os.errno. Fixes #8548

Text tweak

A suggestion to smooth out the text -- if you think it's an improvement, happy to make a larger PR with all the instances of this fixed.