Added a UI option to play all nonlands to the stack instead of the battlefield

[glacials]

By default Cockatrice will only play a card onto the stack if it's an instant or sorcery; otherwise, it plays the card straight onto the battlefield. Rules-wise, this is incorrect behavior -- all spells (i.e. nonlands) use the stack.

This change adds an option, which is turned off by default, to play double-clicked (or single-clicked, depending on your settings) nonland cards onto the stack rather than onto the battlefield.

[Daenyth]

Can you rebase and collapse the commits to more concrete logical units? Probably the "enter the battlefield from stack" commit and "ui option" commit as the only two.

Aside from that, even though this is just a config option, is this something people want? I'm reluctant to add new options since they will make the config ui more confusing, and I've never heard anyone ask for this feature before.

Can you submit it here: http://www.google.com/moderator/#15/e=202784&t=202784.40

[glacials]

Alright, commits have been squashed and the suggestion has been submitted.

This change is something I prefer as a player, as I like to track priority relatively explicitly. However I am just one dude, and if I end up being alone in this preference then I'd agree that it'd be better to keep the interface clean than to merge it.