Revamp of README.

- Add information about default directories.
- Add example of changing a default.
- Mention safety of repos in uninstall section.
Add official debian package repository location.
Eliminate directory not empty errors on uninstall.
Add OFFICIAL variable to script, elide `mv`.
Change mode of executable script and other files.
Add reminder about changing mode.
Change default package dir to reflect README.
Add DESTDIR default of $HOME.
Remove official package, add non-tmp package dir.
Grammar, remove official package references.
Fix some comments, dependencies, and directories.

- Different repository directory.
- Version changed to trailing "-gitp".
- Comment wording.
- I'm not the author. ;)
- Remove versions for dependencies (using stable versions).
Multiple changes that make it WORK again.

- Create the package directory if needed.
- Remove mailq links.
- Remove sendmail link.
- Quote variable.
- Line continuation requires a '\' FFS!
- Update OpenSMTPD git repo URL.