Added ability to create games with descriptions and games continuing chat from other games

Resolves #122.
Resolves #683.
Maybe also #313 as well?

http://jenkins.buttonweavers.com:8080/job/buttonmen-AdmiralJota/291/

These BMInterface additions happened to be enough to tip jenkins over into requiring refactoring for create_game(), validate_game_info() and load_game_parameters() (with attending changes in methods that they call, as well), so it ended up being a more significant set of changes than I'd originally planned. I expect that a careful eye is probably merited, to ensure that I haven't broken anything *too* badly. (Perhaps blackshadowshade should take a look as well, under the assumption that six eyes are better than four.)