Strategy manager now reads the network from file

This happens in the constructor if fighting vs a specific race
Otherwise, gameCommander now calls StrategyManager::onUnitShow() so that
strategyManager can try to create the network when an enemy unit appears.
changed rand to std::rand to avoid conflicts

Also added code but it is in comments for the moment, check later commit
BNet is now loaded when enemy race is discovered
Merge branch 'using-network' into develop