non functional changes

[SwissalpS]

adds:

• github luacheck workflow
• luacheck badge in readme
• CDB badge in readme
• some luacheck related fixups
• some whitespace cleanup for readability and consistancy

I'm aware most of these changes are 'taste' based. Just wanted to let you know that a 'cleaner' version exists.

[SwissalpS]

closing in favour of #11