Comparison to upstream:
- POSIX compliant;
- Add more dialog tools: kdialog;
- Add more screenshot tools: spectacle, xfce4-screenshooter;
- Change work "Nautilus" to "File Manager";
- Fix all shellcheck messages;
- Fix wording of confusing options seen by the user;
- Fix variable names without meaning;
- Remove commented/unused code;
- Remove extraneous messages sent to the user;
- Remove Imgur support; and
- Remove ImageMagic, use tools that support editing: spectacle.
Fixes: https://github.com/ben-grande/qusal/issues/22
