[Fixed] Games with two "human" players

[tomreyn]

It is currently possible to setup a game with two (local, not networked remote) "human" players, which is not intended.

To reproduce:
1. Choose a 2 player map
2. Set player #1 to be CPU
3. Set player #2 to be CPU. Player #1 is automatically set to be "human".
4. Set player #2 to be human, too.

[Omega]

Just out of curiosity, what happens when you start the game? The ability to have multiple human controlled players has been a feature request.

[tomreyn]

You then play the second human player, and the other one just sits around (not sure about this second fact, since I had fog of war on and only played for some seconds).

[tomreyn]

Similar to this issue, here is how you can, on commit 9ecf7276bbf17969def951ab1e8f387add8cfe51, get into a state where you can no longer add a second player:

1. Select a two player map. Set first player to be 'CPU', second player to be 'Human'.
2. Change first player to 'Network'.
3. Change second player to be 'CPU'. This results in the first player becoming 'Human' and the second player being 'Closed'.
4. Try to set the second player to 'CPU'. It fails, the second player immediately jumps back to 'Closed'.