Update base58.h

[r0cketdyne]

Removed unnecessary comments: The original comments were mainly explaining basic coding concepts that are self-explanatory. Removing them helps declutter the code and improves readability.

Used nullptr instead of NULL: nullptr is a safer and more idiomatic way to represent null pointers in modern C++. It provides better type safety and can help prevent bugs related to null pointer dereferencing.

Used std::array instead of raw arrays: std::array provides more safety and flexibility compared to raw arrays. It allows for easier manipulation and avoids the pitfalls associated with raw arrays, such as decay to pointers and lack of size information.

Replaced memcpy with std::copy: std::copy is a more idiomatic and safer way to copy data in C++. It provides better type safety and works seamlessly with STL containers like std::vector.

Used std::vector::assign instead of resize and memcpy: std::vector::assign is a more concise and efficient way to copy data into a vector. It avoids unnecessary resizing and memory reallocation, leading to better performance.

Removed unnecessary explicit conversions: Some explicit conversions, such as (void*)pbegin, are implicit in C++. Removing them simplifies the code and makes it more readable without sacrificing clarity.

Used const references where applicable: Passing arguments by const reference avoids unnecessary copying and improves performance. It also conveys the intent that the function will not modify the argument.

Avoided using raw loops: Utilizing STL algorithms like std::copy and std::reverse improves code readability and maintainability. It also reduces the risk of bugs related to manual loop management.

These refinements aim to make the code more modern, readable, and maintainable while preserving its functionality and performance.