Potential improvements deviating from upstream

[wknapik]

• [ ] Replace tabs with spaces
• [ ] Print errors to stderr
• [ ] Print errors with consistent capitalization
• [ ] Remove extraneous case patterns (e.g. for OS)
• [ ] Maybe improve the way commands are selected to be printed (set -x/set +x)
  code

# helper
show() { (set -x; "$@"); }

# so we can do
show apt-get update

# instead of
set -x
apt-get update
set +x

# and lose the repeating "+ set +x" in the output

• [ ] Cut the script size in half and reduce maintenance to almost nothing (see: comment)