Doesn’t honour WP_PROXY settings

Hi

Our WP platform enforces the use of an HTTP proxy for all outgoing connections.
WP works in this environment by using its WP_HTTP_Proxy class: https://developer.ww.wp.xz.cn/reference/classes/wp_http_proxy/

This plugin however initiates HTTP requests by itself, with many curl_* invocations scattered around the code.
Hence it won’t work in our environment.

By using the standard WP APIs such as WP_HTTP_Proxy the plugin would work in such environments. Added bonus is that the code would probably be a lot cleaner and more future proof.