v0.18.0

Highlights

• split remote features into http and ftp, allowing users who only need HTTP or FTP support to use the
  corresponding feature flag
  • in most cases, users will likely not need to use the ftp feature
• add create_client_with_headers function to allow creating a reqwest::blocking::Client with custom headers
  • this simplifies the process of creating a client with custom headers for HTTP requests
  • this also allows users to create custom clients without importing reqwest crate directly
• add rustls_sys dependency to support rustls as the default TLS backend

Documentation improvements

• update examples on custom HTTP request function oneio::get_http_reader to use create_client_with_headers