Aims to solve the #1088 issue (Multiplayer saved games).
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 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.
- Loading a game, and replacing a player that was human (in the original game) with an AI won't work. The Petra bot won't command the units.
- Loading a game, and replacing a player that was an AI (in the original game) with a human player will produce a strange behaviour where both the player and the AI will send commands to the units
- Loading a game, and replacing a player that was an AI (in the original game) by nothing (unassigned) won't change anything, the AI will still control the units.
All those behaviours should be corrected (The saved state data may hold information regarding the type of player handling a specific slot back when the game was created, and might be contradicting with the init attributes)