Clean up dead code + make style consistent

[TheSunCat]

This pull request covers three chores:

• Deleting the Libraries/STB_Image directory
• Make spacing around parentheses consistent throughout the code and lab documents
• Replace tabs with spaces

Fix inconsistent indentation in projects that use spaces by replacing all tabs with four spaces.

I encountered indentation issues such as this one, when code I write is mixed with code from the template files.

This is because not all text viewers interpret tabs as the same length: for example, most browsers render them as 8 spaces, causing this issue.

Additionally, programmers who use spaces make more money than those who use tabs, so this will ensure students using this engine will earn more.