⚙️for-all-boosters: clean up code

[metacosm]

• review naming style for functions and variables and consistently apply it
• properly identify local vs. global variables (using naming style?)
• use local modifier where appropriate in functions

[metacosm]

Review variable usage and protect them by quotes when appropriate as well.

[metacosm]

Refactor code that worked around lack of associative arrays to use them since we now only work with bash 4+.