setup.sh improved

[casperklein]

Description

• EXIT trap removed
• _unset_vars function removed
• _get_current_directory function replaced with simpler approach
• variable list ordered
• renamed USING_SELINUX to USE_SELINUX like the rest of the USE_ stuff.

Partly discussed here: #1885

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (non-breaking change that does improve existing functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (README.md or ENVIRONMENT.md or the documentation)
• If necessary I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[wernerfred]

So as you removed a function we can safely decrease the image version number 🃏 🤣

[casperklein]

Absolutely 😆

[casperklein]

Probably we cannot get rid of _get_current_directory, because we need an absolute path for docker -v command.

[georglauterbach]

Probably we cannot get rid of _get_current_directory, because we need an absolute path for docker -v command.

🤣 so there it was, the need for an absolute path, hiding in plain site.