Non-blocking API for external event loops

Hi,

libwget2 seems to be missing a non-blocking API? cURL implements this within its curl_multi interface.

Without it, integration into external schedulers/event loops is impossible I think. We use curl in such a way in gnunet, but for a variety of reasons we would prefer to use libwget2 in the future.

For now, however, the blocking API of libwget2 makes this impossible. Are there any plans to do so? I may be willing to mentor such a project as part of GSoC etc as well, but I do not really know how complex such an endeavor is.