This feature implements a load game button for the host in the game setup menu, allowing to load a saved game (without launching the game). When the saved data is loaded, the settings are frozen (except the non-AI-player assignment settings). The host can then decide to start the saved game (if all other human players are ready) or "clear" the saved data, unfreezing the settings. When pressing the start game button, the savedState of the loaded save is compressed, broadcasted to the clients (alongside with the init attributes), decompressed by the clients and a new game is launched, using the init attributes and the saved state.
We might unfreze more settings(victory condition, player color...) in a future diff.