Dotenv 2.0.0

2.0.0 breaking changes:

• Code style changed, including how you called the function. From the previous version, caused a lack of errors and also included bugs (idk why). Please update to this version ASAP.
• .env parsing enhancement

Note: A new dotenv-alt.h file has just added for non-OOP user if someone new in C++! You can even use it by this:

int main() {
  dotenv::load(".env");
  std::cout << dotenv::get("YOUR_KEY") << '\n';

  return 0;
}