Webseeds should be integrated with maxConnectedPeers

[x190]

A properly functioning webseed generates 4 connections and at least one popular torrent (archlinux.iso) has 256 webseeds. This is a major problem, as our limit on open files is 1024, and this torrent will, by itself, trigger a 'too many open files' disaster.

Please see the attached patch for a preliminary, but functional, way forward.

This ticket has been created to separate this issue from the webseed multi-issue ticket #5923.