Add sdhci.debug_quirks2=4 to cmdline.txt when resizing

Only remove 'quiet' from cmdline if splash screen is off

Remove ui and staging components

* Made more specific shellcheck disables
* Fixed variable quoting (SC2086,SC2064)
* Use `$*` expansion instead of `[email protected]` when not using arrays (SC2124)
* Use cleaner `$()` syntax instead of back quotes (SC2006)
* Improved comparator (SC2166)
* Minor improvements in coding style

Tested clean output using: `find -name "*.sh" | xargs -n1 shellcheck -x`.

Move python-games to Raspbian Full and install as a Debian package.