server manager: gameserver on demand launch/stop

[pnxr]

Startup additional instances of servers (min/max number of those as defined in server configuration collection) each time if all servers defined in the configuration of one defined type are 'blocked'. They are considered 'blocked' if A) free servers are full enough 3+/5 players, or B) campagin servers don't have at least 2 joinable slots left for either each Shadow or Light characters.
Stop servers, if they are empty, succeed the min number of active instances supplied and the conditions which led to their starting don't apply anymore.