Character selection screen

[akien-mga]

It should come up after clicking "new game", and let human players select their character. The AI players (currently "non-playing" humans though) would get their character picked up randomly from the remaining ones.

It's not an urgent feature, as there are only 4 characters for the time being and they are a bit featureless. In the future, we'll want more choice and more interesting characters.

[ObaniGemini]

I can maybe try to add 4 characters to the game :)