Function: url-queue-retrieve

Retrieve URL asynchronously and call CALLBACK with CBARGS when finished.
This is like `url-retrieve' (which see for details of the arguments),
but with limits on the degree of parallelism. The variable
`url-queue-parallel-processes' sets the number of concurrent processes.
The variable `url-queue-timeout' sets a timeout.

(fn URL CALLBACK &optional CBARGS SILENT INHIBIT-COOKIES)