added option to ignore unregistered users in chat; switched UserList data storage to QMap to speed up lookups; issue #28 fixed

Revealing a library to a player now grants that player permission to drag cards out of that library onto his own table. This permission is revoked by shuffling the library. The zone view window tracks content changes of the zone for as long as the permission lasts so that card ID changes are kept track of. This hopefully fixes issues #5 and #12.

improved code for automatic joining of persistent games; disconnecting + reconnecting works as it should with ISL

added mutex for RNG, moved game command implementation from S_PH to S_Player in preparation for forwarding of game commands via tunneling interface