Better editing for talk node keys
* The fields start out empty, and it is *allowed* to keep *one of them* empty. (A node only needs one key to be useful, right?
* When the node is saved, empty strings are replaced with `" "`. If this is not harmless to the game logic, then I'll need to make the game aware that either key might be `" "`.
* You cannot type more than 4 characters in these fields (unless there's a way to insert characters I'm not aware of).
* If you put 'buy' in a field, it automatically becomes 'purc'.
* There is a note next to the response keys (kind of squished in the corner) enumerating the special logic of the in-game Buy and Sell buttons.
Celtic Minstrel
9fd468f578
