A bunch of performance improvements, style updates and use more "rusty" code

[jewlexx]

List of changes:

• Fixed clippy issues and formatting
• Use impl AsRef<Path> for the path argument to relax restrictions and be more intuitive and friendly, particularly on Windows which has paths that dont conform to utf8 and therefore cannot be put in a &str
• Removed redundant code which either evaluated, always the same or could be inlined to remove function calls and improve performance
• Remove redundant type annotation (because the rust type system is incredible and can deal with that for us :))
• Use struct rather than function. This allows us to implement a lot more custom behaviour, for example, what I did, implement the Iterator trait so that it can be treated the same as any other iterator.
• Add documentation

[ParthJadhav]

Merging this, let's work on those comments later on. Thank you so much for amazing work @jewlexx