Options>Discussion should warn if track/pingbacks won't work

[hansengel]

If allow_url_fopen is set to Off and the Curl extension isn't loaded, trackbacks and pingbacks won't work. There should be some kind of notification that they will not work on the Options>Discussion page when they enabled (e.g. when enabled, check if track/pingbacks are possible, and if not, show a notification).

Thanks to ​Donncha for the inspiration.

[darkdragon]

See also #4779.

[ffemtcj]

No Patch. Moved to 2.7

[hansengel]

Adds alert to Settings > Discussion

[Otto42]

Suggestion: Since we're using wp_remote_fopen for all this sort of thing now, make a checker function near it in functions.php and use that instead.

function wp_remote_fopen_check() {
	if (ini_get( 'allow_url_fopen' ) || function_exists( 'curl_init' ))
		return true;
	return false;
}

[jacobsantos]

No longer an issue, pingbacks and trackbacks uses the HTTP API in 2.7.